Add default constructor to datamodels and deprecate the maker_utils

[WilliamJamieson]

This PR adds the type(datamodel).create_default(**kwargs) instance constructor to each of the datamodel types. This is equivalent to calling maker_utils.mk_datamodel(type(datamodel), **kwargs). This prevents users from accidentally working directly with un-wrapped node objects, external users should be working through the datamodel objects not the nodes. This also simplifies the method to generate a "default" model.

This is the first step in moving the handling of datamodel creation in romancal. The next step will be adding constructor methods construct datamodels from datamodels of a different type where this makes sense.

Tasks

• Update or add relevant roman_datamodels tests.
• Update relevant docstrings and / or docs/ page.
• Does this PR change any API used downstream? (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).
  • Start a romancal regression test (https://github.com/spacetelescope/RegressionTests/actions/workflows/romancal.yml) with this branch installed ("git+https://github.com/<fork>/rad@<branch>").

News fragment change types:

• changes/<PR#>.feature.rst: new feature
• changes/<PR#>.bugfix.rst: fixes an issue
• changes/<PR#>.doc.rst: documentation change
• changes/<PR#>.removal.rst: deprecation or removal of public API
• changes/<PR#>.misc.rst: infrastructure or miscellaneous change

[codecov]

Codecov Report

Attention: Patch coverage is 96.26866% with 5 lines in your changes missing coverage. Please review.

Project coverage is 97.28%. Comparing base (087a60d) to head (890385e).
Report is 81 commits behind head on main.

Files with missing lines	Patch %	Lines
src/roman_datamodels/maker_utils.py	0.00%	4 Missing ⚠️
src/roman_datamodels/datamodels/_core.py	88.88%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #436      +/-   ##
==========================================
- Coverage   97.56%   97.28%   -0.29%     
==========================================
  Files          30       38       +8     
  Lines        2788     3420     +632     
==========================================
+ Hits         2720     3327     +607     
- Misses         68       93      +25     

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[mairanteodoro]

Looks good to me!