Refactor Data properties in component schemas

[bkoelman]

This is required for adding atomic:operations support.

Using a Data base class is a leftover from an earlier JADNC version. Since then, we've changed serialization to use containment, so this PR adapts accordingly. The advantage is that we can now rely on the property declaration order, so we don't need to reorder ourselves like we used to.

QUALITY CHECKLIST

• Changes implemented in code
• Complies with our contributing guidelines
• Adapted tests
• N/A: Documentation updated

[codecov]

Codecov Report

Attention: Patch coverage is 90.90909% with 3 lines in your changes are missing coverage. Please review.

Project coverage is 90.79%. Comparing base (1bdee8b) to head (10980e6).

Files	Patch %	Lines
...enApi/SwaggerComponents/DocumentSchemaGenerator.cs	75.00%	1 Missing and 1 partial ⚠️
...re.OpenApi/JsonApiRequestFormatMetadataProvider.cs	0.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           openapi    #1522      +/-   ##
===========================================
- Coverage    90.85%   90.79%   -0.07%     
===========================================
  Files          396      397       +1     
  Lines        13115    13023      -92     
  Branches      2078     2075       -3     
===========================================
- Hits         11916    11824      -92     
  Misses         781      781              
  Partials       418      418              

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