Add CompilerPlugin support in Artifact.scala, JsonSchemas, and UI

[vidishagawas121]

Summary

This PR adds full support for the CompilerPlugin platform across the backend and API.

Changes include:

• Added CompilerPlugin case in Platform.scala and updated ordering.
• Updated all pattern matches on platform and binaryVersion.platform in Artifact.scala to handle CompilerPlugin, raising UnsupportedOperationException where appropriate.
• Ensured JSON serialization/deserialization works by updating JsonSchemas.scala.
• Updated UI templates to show a CompilerPlugin section where relevant.
• Added parsing and platform tests for CompilerPlugin in PlatformTests.

Testing

• Verified all types and values exist in Artifact.scala.
• Checked JsonSchemas for duplicate givens (none found).
• Existing tests pass with sbt test.
• CI pipeline should pass on a clean build.

Mentors

@adpi2 @kannupriyakalra

Related Issue

Part of #865