JP-4275: Store mosaic members' WCS objects along with some metadata in ImageModels

[tapastro]

Partially resolves JP-4275

This PR allows ImageModels to store WCS objects along with associated filenames and sky reference positions, such that downstream WFSS spectral processing has access to the tweaked WCS objects.

*** WIP ***

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

❌ Patch coverage is 68.18182% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.60%. Comparing base (86780fb) to head (15e0c90).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
src/stdatamodels/fits_support.py	33.33%	6 Missing ⚠️
src/stdatamodels/jwst/datamodels/member_wcs.py	91.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #754      +/-   ##
==========================================
- Coverage   90.71%   90.60%   -0.11%     
==========================================
  Files          99      100       +1     
  Lines        4597     4619      +22     
==========================================
+ Hits         4170     4185      +15     
- Misses        427      434       +7     

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