Compute undistorted coordinates

[nden]

Resolves RCAL-997

Closes #1599

This PR addresses a request by SSC to provide a way to compute undistorted pixels.
It's a temporary fix. Eventually a coordinate frame should be added to the WCS pipeline and the transforms should be
split in the distortion file.

The function is private on purpose as it will change in the future and will be finally removed.

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 42.85714% with 4 lines in your changes missing coverage. Please review.

Project coverage is 78.11%. Comparing base (6534f9d) to head (bb39ce0).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
romancal/assign_wcs/__init__.py	42.85%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1612      +/-   ##
==========================================
- Coverage   78.14%   78.11%   -0.04%     
==========================================
  Files         116      116              
  Lines        7629     7635       +6     
==========================================
+ Hits         5962     5964       +2     
- Misses       1667     1671       +4     

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[schlafly]

Thanks Nadia, looks reasonable to me. Shall I go ahead and merge?