use ValidationError from asdf.exceptions instead of jsonschema

[braingram]

By using asdf.exceptions.ValidationError asdf will be free to make this error hopefully more useful and to untie it from jsonschema.

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/Roman-Developers-Pull-Requests/278/

passed all except for known failure test_one_group_small_buffer_fit_ols[none] see spacetelescope/romancal#769

[codecov]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (c0a084d) 94.47% compared to head (cc0835a) 94.47%.

❗ Current head cc0835a differs from pull request most recent head f7a972e. Consider uploading reports for the commit f7a972e to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #234   +/-   ##
=======================================
  Coverage   94.47%   94.47%           
=======================================
  Files          23       23           
  Lines        1628     1628           
=======================================
  Hits         1538     1538           
  Misses         90       90           

Impacted Files	Coverage Δ
src/roman_datamodels/datamodels/_core.py	89.67% <100.00%> (ø)
src/roman_datamodels/stnode/_node.py	87.97% <100.00%> (ø)
src/roman_datamodels/validate.py	93.75% <100.00%> (ø)

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[WilliamJamieson]

I would like to see this change; however, everyone should agree that this is the way to proceed.

[braingram]

Regression tests run:
https://plwishmaster.stsci.edu:8081/job/RT/job/Roman-Developers-Pull-Requests/278/

passed all except for known failure test_one_group_small_buffer_fit_ols[none] see spacetelescope/romancal#769

[PaulHuwe]

LGTM