only load patch table when needed

[braingram]

This PR modifies the mosaic pipeline and patch match submodule to only load the patch table when required (instead of at import).

Regression tests: https://github.com/spacetelescope/RegressionTests/actions/runs/10404395165

Closes #1366

Checklist

• added entry in CHANGES.rst under the corresponding subsection
• updated relevant tests
• updated relevant documentation
• updated relevant milestone(s)
• added relevant label(s)
• ran regression tests, post a link to the Jenkins job below. How to run regression tests on a PR

[codecov]

Codecov Report

Attention: Patch coverage is 16.66667% with 5 lines in your changes missing coverage. Please review.

Project coverage is 78.48%. Comparing base (482ef5c) to head (1993203).
Report is 237 commits behind head on main.

Files with missing lines	Patch %	Lines
romancal/pipeline/mosaic_pipeline.py	0.00%	4 Missing ⚠️
romancal/patch_match/patch_match.py	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1367      +/-   ##
==========================================
- Coverage   78.61%   78.48%   -0.13%     
==========================================
  Files         117      117              
  Lines        7856     7861       +5     
==========================================
- Hits         6176     6170       -6     
- Misses       1680     1691      +11     

Flag	Coverage Δ		*Carryforward flag
nightly	62.24% <ø> (ø)		Carriedforward from 482ef5c

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[schlafly]

Thanks Brett, that looks good to me!