Remove noqas in transform models

[emolter]

Closes #390

This PR makes a few small changes to the Snell and GrismObject models that allow for the removal of some style rule ignores.

With this PR, all the comments in #383 that prompted the creation of #390 and sub-tickets are addressed, so we should be ok to close out that ticket.

Tasks

• update or add relevant tests
• update relevant docstrings and / or docs/ page
• Does this PR change any API used downstream? (if not, label with no-changelog-entry-needed)
  • write news fragment(s) in changes/: echo "changed something" > changes/<PR#>.<changetype>.rst (see below for change types)
  • run jwst regression tests with this branch installed ("git+https://github.com/<fork>/stdatamodels@<branch>")

news fragment change types...

• changes/<PR#>.feature.rst: new feature
• changes/<PR#>.bugfix.rst: fixes an issue
• changes/<PR#>.doc.rst: documentation change
• changes/<PR#>.removal.rst: deprecation or removal of public API
• changes/<PR#>.misc.rst: infrastructure or miscellaneous change

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.13%. Comparing base (1a75983) to head (2f233c2).
⚠️ Report is 97 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #597   +/-   ##
=======================================
  Coverage   90.12%   90.13%           
=======================================
  Files         111      111           
  Lines        5317     5321    +4     
=======================================
+ Hits         4792     4796    +4     
  Misses        525      525           

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[emolter]

https://github.com/spacetelescope/RegressionTests/actions/runs/18233515937