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

• [x] Added entry in CHANGES.rst under the corresponding subsection
• [x] updated relevant tests
• [x] updated relevant documentation
• [ ] Passed romancal regression testing on Jenkins / PLWishMaster. Link: https://plwishmaster.stsci.edu:8081/job/RT/job/romancal/692/

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

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

Additional details and impacted files

```diff @@ 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.

[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.