Support newer Clang versions (>= 16)

[dc-mak]

In file included from /home/dhruv/c-tree-carver/cpp/src/reachability_analyzer.cpp:82:
/home/dhruv/c-tree-carver/cpp/src/traverser.hpp: In member function ‘void Traverser::down_casted(const clang::DesignatedInitExpr*, int)’:
/home/dhruv/c-tree-carver/cpp/src/traverser.hpp:340:32: error: ‘const class clang::DesignatedInitExpr::Designator’ has no member named ‘getField’; did you mean ‘getFieldLoc’?
  340 |                 traverse(child.getField(), depth + 1);
      |                                ^~~~~~~~
      |                                getFieldLoc

Not backwards compatible, since 17: Rename clang::DesignatedInitExpr::Designator::getField() => getFieldDecl() (see llvm/llvm-project@b51a03e#diff-03e60ab06f82e27e971dc7c0816e51e2a984da855607560e33c94094ac1622c9R5177).

/home/dhruv/c-tree-carver/cpp/src/traverser.hpp: In member function ‘void Traverser::down_casted(const clang::TypeOfType*, int)’:
/home/dhruv/c-tree-carver/cpp/src/traverser.hpp:435:24: error: ‘const class clang::TypeOfType’ has no member named ‘getUnderlyingType’
  435 |         traverse(type->getUnderlyingType(), depth);
      |                        ^~~~~~~~~~~~~~~~~

Not backwards compatible, since 16: Rename class clang::TypeOfType::getUnderlyingType() => getUnmodifiedType() (see llvm/llvm-project@60727d8#diff-c4d7904edf8b990b1744903f7bda4ba256bd6709519f5a85d3015eb141506dfaR4614).

/home/dhruv/c-tree-carver/cpp/src/traverser.hpp: In member function ‘void Traverser::down_casted(const clang::TemplateSpecializationType*, int)’:
/home/dhruv/c-tree-carver/cpp/src/traverser.hpp:472:33: error: ‘begin’ was not declared in this scope
  472 |         for (const auto &arg : *type) {
      |                                 ^~~~
/home/dhruv/c-tree-carver/cpp/src/traverser.hpp:472:33: note: suggested alternatives:
In file included from /usr/include/c++/11/array:41,
                 from /usr/include/c++/11/tuple:39,
                 from /usr/include/c++/11/functional:54,
                 from /usr/include/c++/11/pstl/glue_algorithm_defs.h:13,
                 from /usr/include/c++/11/algorithm:74,
                 from /usr/lib/llvm-19/include/llvm/ADT/Hashing.h:52,
                 from /usr/lib/llvm-19/include/llvm/ADT/ArrayRef.h:12,
                 from /usr/lib/llvm-19/include/llvm/ADT/APFloat.h:19,
                 from /usr/lib/llvm-19/include/clang/AST/APNumericStorage.h:12,
                 from /usr/lib/llvm-19/include/clang/AST/Decl.h:16,
                 from /home/dhruv/c-tree-carver/cpp/src/debug_printers.hpp:42,
                 from /home/dhruv/c-tree-carver/cpp/src/reachability_analyzer.hpp:82,
                 from /home/dhruv/c-tree-carver/cpp/src/reachability_analyzer.cpp:79:
/usr/include/c++/11/bits/range_access.h:108:37: note:   ‘std::begin’
  108 |   template<typename _Tp> const _Tp* begin(const valarray<_Tp>&) noexcept;
      |                                     ^~~~~
In file included from /usr/include/c++/11/utility:76,
                 from /usr/include/c++/11/optional:36,
                 from /usr/lib/llvm-19/include/llvm/ADT/APInt.h:24,
                 from /usr/lib/llvm-19/include/llvm/ADT/APFloat.h:18,
                 from /usr/lib/llvm-19/include/clang/AST/APNumericStorage.h:12,
                 from /usr/lib/llvm-19/include/clang/AST/Decl.h:16,
                 from /home/dhruv/c-tree-carver/cpp/src/debug_printers.hpp:42,
                 from /home/dhruv/c-tree-carver/cpp/src/reachability_analyzer.hpp:82,
                 from /home/dhruv/c-tree-carver/cpp/src/reachability_analyzer.cpp:79:
/usr/include/c++/11/initializer_list:90:5: note:   ‘std::begin’
   90 |     begin(initializer_list<_Tp> __ils) noexcept
      |     ^~~~~
In file included from /usr/lib/llvm-19/include/llvm/Support/VirtualFileSystem.h:27,
                 from /usr/lib/llvm-19/include/clang/Basic/FileManager.h:30,
                 from /usr/lib/llvm-19/include/clang/Basic/SourceManager.h:39,
                 from /home/dhruv/c-tree-carver/cpp/src/debug_printers.hpp:43,
                 from /home/dhruv/c-tree-carver/cpp/src/reachability_analyzer.hpp:82,
                 from /home/dhruv/c-tree-carver/cpp/src/reachability_analyzer.cpp:79:
/usr/lib/llvm-19/include/llvm/Support/Path.h:122:16: note:   ‘llvm::sys::path::begin’
  122 | const_iterator begin(StringRef path, Style style = Style::native);
      |                ^~~~~
In file included from /home/dhruv/c-tree-carver/cpp/src/reachability_analyzer.cpp:82:
/home/dhruv/c-tree-carver/cpp/src/traverser.hpp:472:33: error: ‘end’ was not declared in this scope
  472 |         for (const auto &arg : *type) {
      |                                 ^~~~
/home/dhruv/c-tree-carver/cpp/src/traverser.hpp:472:33: note: suggested alternatives:
In file included from /usr/include/c++/11/array:41,
                 from /usr/include/c++/11/tuple:39,
                 from /usr/include/c++/11/functional:54,
                 from /usr/include/c++/11/pstl/glue_algorithm_defs.h:13,
                 from /usr/include/c++/11/algorithm:74,
                 from /usr/lib/llvm-19/include/llvm/ADT/Hashing.h:52,
                 from /usr/lib/llvm-19/include/llvm/ADT/ArrayRef.h:12,
                 from /usr/lib/llvm-19/include/llvm/ADT/APFloat.h:19,
                 from /usr/lib/llvm-19/include/clang/AST/APNumericStorage.h:12,
                 from /usr/lib/llvm-19/include/clang/AST/Decl.h:16,
                 from /home/dhruv/c-tree-carver/cpp/src/debug_printers.hpp:42,
                 from /home/dhruv/c-tree-carver/cpp/src/reachability_analyzer.hpp:82,
                 from /home/dhruv/c-tree-carver/cpp/src/reachability_analyzer.cpp:79:
/usr/include/c++/11/bits/range_access.h:110:37: note:   ‘std::end’
  110 |   template<typename _Tp> const _Tp* end(const valarray<_Tp>&) noexcept;
      |                                     ^~~
In file included from /usr/include/c++/11/utility:76,
                 from /usr/include/c++/11/optional:36,
                 from /usr/lib/llvm-19/include/llvm/ADT/APInt.h:24,
                 from /usr/lib/llvm-19/include/llvm/ADT/APFloat.h:18,
                 from /usr/lib/llvm-19/include/clang/AST/APNumericStorage.h:12,
                 from /usr/lib/llvm-19/include/clang/AST/Decl.h:16,
                 from /home/dhruv/c-tree-carver/cpp/src/debug_printers.hpp:42,
                 from /home/dhruv/c-tree-carver/cpp/src/reachability_analyzer.hpp:82,
                 from /home/dhruv/c-tree-carver/cpp/src/reachability_analyzer.cpp:79:
/usr/include/c++/11/initializer_list:101:5: note:   ‘std::end’
  101 |     end(initializer_list<_Tp> __ils) noexcept
      |     ^~~
In file included from /usr/lib/llvm-19/include/llvm/Support/VirtualFileSystem.h:27,
                 from /usr/lib/llvm-19/include/clang/Basic/FileManager.h:30,
                 from /usr/lib/llvm-19/include/clang/Basic/SourceManager.h:39,
                 from /home/dhruv/c-tree-carver/cpp/src/debug_printers.hpp:43,
                 from /home/dhruv/c-tree-carver/cpp/src/reachability_analyzer.hpp:82,
                 from /home/dhruv/c-tree-carver/cpp/src/reachability_analyzer.cpp:79:
/usr/lib/llvm-19/include/llvm/Support/Path.h:127:16: note:   ‘llvm::sys::path::end’
  127 | const_iterator end(StringRef path);
      |                ^~~

Backwards compatible, since 16: Move clang::TemplateSpecializationType::begin() => template_arguments() (see llvm/llvm-project@1acffe8#diff-c4d7904edf8b990b1744903f7bda4ba256bd6709519f5a85d3015eb141506dfaR5415).