Remove defaultLoopRender and avoid fsnotify dependency

[georgefst]

See #370. This branch is to demonstrate how little fsnotify-dependent code this library has, and to give me somewhere to point to for projects in which I'm using diagrams with the Wasm backend.

Currently, building for Wasm with GHC 9.10 requires a cabal.project with:

packages: .

if arch(wasm32)
  active-repositories: hackage.haskell.org, head.hackage.ghc.haskell.org

Then, for example, nix shell gitlab:haskell-wasm/ghc-wasm-meta?rev=56dfe2478cae35ded335261c854bb8b2a5e7f4d2#all_9_10 -c wasm32-wasi-cabal build all works.

[georgefst]

Actually, reading #370 again, it seems @byorgey is open to the idea of removing this function entirely, so perhaps this shouldn't be a draft...

[byorgey]

@georgefst Yeah, definitely open to removing it entirely!