RAD-155: Add 'basic' schema to 'wfi_mosaic'

[nden]

Resolves RCAL-nnnn

Closes #

The changes in this PR correspond to RAD-155 changes in spacetelescope/rad#390.
pyproject should be updated before merging

Checklist

• Added entry in CHANGES.rst under the corresponding subsection
• updated relevant tests
• updated relevant documentation
• Passed romancal regression testing on Jenkins / PLWishMaster. Link: https://plwishmaster.stsci.edu:8081/job/RT/job/romancal/XXX/

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.51%. Comparing base (087a60d) to head (a42188a).
Report is 6 commits behind head on main.

❗ Current head a42188a differs from pull request most recent head 355494e. Consider uploading reports for the commit 355494e to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #328      +/-   ##
==========================================
- Coverage   97.56%   97.51%   -0.06%     
==========================================
  Files          30       32       +2     
  Lines        2788     2972     +184     
==========================================
+ Hits         2720     2898     +178     
- Misses         68       74       +6     

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[nden]

@PaulHuwe Thanks for the review. This is ready now for final review.

[PaulHuwe]

LGTM.