[dlang] Support extention objects in arrays and the default field

[tom-tan]

This request contains the following improvements to dlang codegen.

[Implemented] Support extension objects in arrays

The current dlang code-generated parser rejects the extension objects such as cwltool:CUDARequirement in the requirement field. This request is to accept such extension objects in parser level.

Note: Extension fields such as https://schema.org/name as explained in the user guide are already supported in schema-salad-d level without changing dlang codegen.

[Not yet] Support the default field

The current dlang codegen ignores the default field. Therefore schema-salad-d cannot generate the code to set the default value from the declaration. This request is to fix this issue by adding the @defalultValue attribute to the generated field declarations.

[codecov]

Codecov Report

Attention: Patch coverage is 91.66667% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 83.38%. Comparing base (74a5ba5) to head (9ba4f9a).
Report is 8 commits behind head on main.

Files	Patch %	Lines
schema_salad/dlang_codegen.py	91.66%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #825      +/-   ##
==========================================
+ Coverage   83.35%   83.38%   +0.02%     
==========================================
  Files          22       22              
  Lines        4818     4838      +20     
  Branches     1303     1310       +7     
==========================================
+ Hits         4016     4034      +18     
- Misses        527      528       +1     
- Partials      275      276       +1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.