RCAL-1016 move skycell wcs reading into resample

[braingram]

Resolves https://jira.stsci.edu/browse/RCAL-1016

Closes #1615
Closes #1643

Regtests (with skycell wcs disabled for outlier detection) show 1 failure due to a resample regtest using an association with a skycell target. With this PR that association uses the skycell and produces the expected difference:
https://github.com/spacetelescope/RegressionTests/actions/runs/13523271813/attempts/2

Regtests (with skycell wcs enabled for outlier detection):
https://github.com/spacetelescope/RegressionTests/actions/runs/13523271813
show an additional difference for test_mos_skycell_pipeline when comparing the result and truth files.

Tasks

• request a review from someone specific, to avoid making the maintainers review every PR
• add a build milestone, i.e. 24Q4_B15 (use the latest build if not sure)
• Does this PR change user-facing code / API? (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)
  • update or add relevant tests
  • update relevant docstrings and / or docs/ page
  • start a regression test and include a link to the running job (click here for instructions)
    • Do truth files need to be updated ("okified")?
      • after the reviewer has approved these changes, run okify_regtests to update the truth files
• if a JIRA ticket exists, make sure it is resolved properly

news fragment change types...

• changes/<PR#>.general.rst: infrastructure or miscellaneous change
• changes/<PR#>.docs.rst
• changes/<PR#>.stpipe.rst
• changes/<PR#>.associations.rst
• changes/<PR#>.scripts.rst
• changes/<PR#>.mosaic_pipeline.rst
• changes/<PR#>.patch_match.rst

steps

• changes/<PR#>.dq_init.rst
• changes/<PR#>.saturation.rst
• changes/<PR#>.refpix.rst
• changes/<PR#>.linearity.rst
• changes/<PR#>.dark_current.rst
• changes/<PR#>.jump_detection.rst
• changes/<PR#>.ramp_fitting.rst
• changes/<PR#>.assign_wcs.rst
• changes/<PR#>.flatfield.rst
• changes/<PR#>.photom.rst
• changes/<PR#>.flux.rst
• changes/<PR#>.source_detection.rst
• changes/<PR#>.tweakreg.rst
• changes/<PR#>.skymatch.rst
• changes/<PR#>.outlier_detection.rst
• changes/<PR#>.resample.rst
• changes/<PR#>.source_catalog.rst

[codecov]

Codecov Report

Attention: Patch coverage is 64.00000% with 27 lines in your changes missing coverage. Please review.

Project coverage is 80.12%. Comparing base (7484c38) to head (67a586d).

Files with missing lines	Patch %	Lines
romancal/pipeline/mosaic_pipeline.py	5.55%	17 Missing ⚠️
romancal/patch_match/patch_match.py	84.61%	8 Missing ⚠️
romancal/resample/resample.py	60.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1642      +/-   ##
==========================================
+ Coverage   80.02%   80.12%   +0.10%     
==========================================
  Files         112      111       -1     
  Lines        6844     6748      -96     
==========================================
- Hits         5477     5407      -70     
+ Misses       1367     1341      -26     

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