Rcal 860 Allow roman datamodel as input to the exposure pipeline

[ddavis-stsci]

Resolves RCAL-860

Closes #1284

This PR allows the exposure pipeline to accept a roman datamodel as an input.

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
  The general regtests are failing at tweakreg (being worked on), https://github.com/spacetelescope/RegressionTests/actions/runs/9778658002/job/26996524484
  But the test to see if the exposure pipeline accepts a roman data model is passing,
  https://github.com/spacetelescope/RegressionTests/actions/runs/9778307535

[codecov]

Codecov Report

Attention: Patch coverage is 30.43478% with 16 lines in your changes missing coverage. Please review.

Project coverage is 79.37%. Comparing base (74a137c) to head (b6290fb).
Report is 233 commits behind head on main.

Files with missing lines	Patch %	Lines
romancal/pipeline/exposure_pipeline.py	0.00%	16 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1296      +/-   ##
==========================================
- Coverage   79.39%   79.37%   -0.03%     
==========================================
  Files         117      117              
  Lines        8076     8086      +10     
==========================================
+ Hits         6412     6418       +6     
- Misses       1664     1668       +4     

Flag	Coverage Δ		*Carryforward flag
nightly	62.84% <ø> (ø)		Carriedforward from 74a137c

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[schlafly]

Looks good to me, thanks!