More tests, workflows PR comment for feature test

[varunghat]

Added the following regression tests:

• Clicks and modifiers get typed as "M", which caused some issues previously with clicks and diacritics getting swapped where they shouldn't. Added a test to make sure the behaviour is as intended.
• c-cedilla is a special case handled in denorm(), as well as 20 special-cases for features. Added a test to ensure these are not changed

Added the following new test

• test-cross-inventory-integrity.R checks if
  • any (Source, Glottocode, LanguageName, SpecificDialect, BibtexKey) repeats with the same InventoryID , which implies there's two languages with the same InventoryID
  • Checks if all BibtexKey map to a valid Bibtex entry in phoible-references.bib
  • Checks if each InventoryID in bibtex mapping file is present in the final phoible.csv and vice-versa

Added the following extra test to test-inventory-metadata.R

• Check if the ISOcodes present in glottolog match the ISOcodes present in phoible (With certain exceptions where glottolog keeps the older ISOcodes)

Excluded test-phonemes.R from github workflows test suite, but added it as a separate job which writes the output as a comment in the PR

Added tasks to pixi.toml (exactly the same as #398)

[varunghat]

Split into two workflows now (Since PR from forked repo does not have write permissions)

First workflow runs the Feature test (test-phonemes.R) first and stores data. Then runs the tests suite.
Second workflow runs on completion of the first, and writes the PR comment.

Verified the workflow on my forked branch, PR comment works with PR from a forked repo. Will work once the new workflow file gets added to master.

Current test fails are the 5 ISOcodes that do not match with glottolog (More info in this PR that fixes them: #403)