Db writer fix

[Alexander-Sol]

Writing an XML protein database displays non-deterministic behavior. HashSets (which are inherently unordered) of Modifications are enumerated and the results written to the database one at a time. This can result in the database listing mods in different orders if the write operation is performed multiple times.

This PR fixes the order in which mods are written to the database, with the end goal of improving stability within MetaMorpheus.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.28%. Comparing base (dc44773) to head (3fb1b33).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #820      +/-   ##
==========================================
+ Coverage   77.26%   77.28%   +0.01%     
==========================================
  Files         218      218              
  Lines       33027    33037      +10     
  Branches     3426     3426              
==========================================
+ Hits        25519    25531      +12     
+ Misses       6938     6937       -1     
+ Partials      570      569       -1     

Files with missing lines	Coverage Δ
mzLib/UsefulProteomicsDatabases/ProteinDbWriter.cs	96.81% <100.00%> (+0.63%)	⬆️