Retain id and other top-level attributes in merge_property_trees

[braingram]

This PR updates merge_property_trees to retain the schema id (and other "top level" items/attributes). This fixes the issue where model.schema["id"] does not match the "id" of the schema (see #308).

This PR also drops the use of OrderedDict fixing #40.

Finally the CI goblins revealed that shuffling order of tests can cause test_defined_models_up_to_date to fail:
https://github.com/spacetelescope/stdatamodels/actions/runs/11901768169/job/33165405951
if executed after test_model_with_nonstandard_primary_array which defines a test model class that isn't prefixed with _. This PR adds a _ prefix to the test class to avoid this intermittent issue.

Fixes: https://jira.stsci.edu/browse/JP-2137
Closes #308
Closes #40

Regression tests: https://github.com/spacetelescope/RegressionTests/actions/runs/11914331392
produce 5 "failures" which look like improvements to me. The failures are in the niriss ami tests:

        Headers contain differences:
         Keyword          has different values:
            a> AMI OIFITS analysis data model
            b> OIFITS required meta data (not otherwise defined in core.schema)

Since this PR retains the top level schema items this is keeping the title from the datamodel schema:

stdatamodels/src/stdatamodels/jwst/datamodels/schemas/amioi.schema.yaml

Line 5 in 2c39853

title: AMI OIFITS analysis data model

which in the truth file ends up being overwritten by the referenced oifits schema:

stdatamodels/src/stdatamodels/jwst/datamodels/schemas/oifits.schema.yaml

Line 5 in 2c39853

title: OIFITS required meta data (not otherwise defined in core.schema)

Keeping the datamodel schema title seems preferable.

Tasks

• update or add relevant 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)
  • run jwst regression tests with this branch installed ("git+https://github.com/<fork>/stdatamodels@<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

All modified and coverable lines are covered by tests ✅

Project coverage is 67.56%. Comparing base (1e16207) to head (3aad51e).
Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #364      +/-   ##
==========================================
+ Coverage   67.52%   67.56%   +0.03%     
==========================================
  Files         114      114              
  Lines        5916     5919       +3     
==========================================
+ Hits         3995     3999       +4     
+ Misses       1921     1920       -1     

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[emolter]

Looks good, just two small comments

[braingram]

I'm going to wait to merge and okify this until tomorrow.

[braingram]

Regtest started for okifying: https://github.com/spacetelescope/RegressionTests/actions/runs/11954122369