feat(ci): add jsonschema lint job to lint and fix linting issues in JSON Schemas

[Karan-Palan]

Description

ref #670 (comment)

1. Created a jsonschema lint job in CI to check linting issues and commit the fixed schema files

2. Linting rules fixed:

   • Unknown keywords prefixed: All custom keywords like errorMessage, $anchor, and spectral-runtime were prefixed with x- to become x-errorMessage, x-$anchor, and x-spectral-runtime
   • Unnecessary allOf wrappers removed: The complex allOf structures were simplified for better performance

Note

I, along with Juan (JSON Schema TSC member) are defining linting rules for JSON Schema as a Part of a GSoC (Google Summer of code) project here - https://github.com/Karan-Palan/JSON-Schema-Linting, and implementing their auto-fixes here - https://github.com/sourcemeta/jsonschema/blob/main/docs/lint.markdown. We have recently added many rules prefixing unknown keywords with x- which will be introduced in the newer JSON Schema drafts.

[daveshanley]

LGTM! thank you!