feat: Implementing support for full config of subform component

[wrt95]

Description

• Implementing full support for configuration of SubForm components.
• Design is not updated as it will be done in Update subForm tableColumns config to comply with UX design #13683. Temporary design:
  

Related Issue(s)

• Add tableColumns config #13655
• Support full configuration of SubForm component #13476

Verification

• Your code builds clean without any errors or warnings
• Manual testing done (required)
• Relevant automated test added (if you find this hard, leave it and we'll help out)

Documentation

• User documentation is updated with a separate linked PR in altinn-studio-docs. (if applicable)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.28%. Comparing base (57f01e1) to head (e4c3af6).
Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #13782      +/-   ##
==========================================
+ Coverage   95.27%   95.28%   +0.01%     
==========================================
  Files        1635     1641       +6     
  Lines       21828    21881      +53     
  Branches     2567     2572       +5     
==========================================
+ Hits        20796    20849      +53     
  Misses        787      787              
  Partials      245      245              

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

[Jondyr]

Nice! 🚀

Small nitpick/question: