Fill in gaps in identification code testing

[acesnik]

There are a few gaps in the identification code testing that are actually pretty pertinent to these changes in Modification.

e.g. https://codecov.io/gh/smith-chem-wisc/ProteoformSuite/src/ca455bbdadd0d5bc58a7ddfde977014b797b957e/ProteoformSuiteInternal/Proteoform.cs#L211

[leahvschaffer]

That link isn't working for me do you mind showing me what lines are uncovered?

Also I think we should consider getting Jenkins working for PS too for stuff like this. Maybe Sheeren would have time after the WPF stuff is done. A bandaid might be to do a full run unit test and the values should all match