RCAL-804: Split cal_step into L2 & L3

[PaulHuwe]

Resolves RCAL-804

Closes #

This PR splits the cal_step datamodels into L2 and L3 versions.

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/692/

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.33%. Comparing base (087a60d) to head (b54fe35).
Report is 10 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #334      +/-   ##
==========================================
- Coverage   97.56%   97.33%   -0.23%     
==========================================
  Files          30       31       +1     
  Lines        2788     2965     +177     
==========================================
+ Hits         2720     2886     +166     
- Misses         68       79      +11     

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[PaulHuwe]

NOTE: these changes require updates to romancal regression test files as shown in the Jenkins URL.

[ddavis-stsci]

LGTM

[nden]

The latest changes in RAD are related to this PR. Since merging this will point roman_datamodels back to rad/main I'm going to go ahead and merge it so I can get romancal installable again.