feat: add API descriptor with API_SPECTRAL with AsyncAPI/OpenAPI support

[pjungermann]

Add API descriptor as modified copy of the OPENAPI descriptor. Deprecate the contained linter OPENAPI_SPECTRAL.

Add .spectral.yaml as default config file to TEMPLATE/ as modified copy of .openapirc.yml with rulesets for AsyncAPI and OpenAPI (previously, only OpenAPI).

Fixes #3387

Proposed Changes

1. Adds API_SPECTRAL as modified copy of OPENAPI_SPECTRAL.
2. Supports AsyncAPI and OpenAPI (filenames, file contents, etc.).
3. Uses .spectral.yaml as config filename and provides a default file at TEMPLATE/ with rulesets for AsyncAPI and OpenAPI.
4. Deprecates OPENAPI_SPECTRAL (and therefore, OPENAPI)

Readiness Checklist

Author/Contributor

• Add entry to the CHANGELOG listing the change and linking to the corresponding issue (if appropriate)
• If documentation is needed for this change, has that been included in this pull request

Reviewing Maintainer

• Label as breaking if this is a large fundamental change
• Label as either automation, bug, documentation, enhancement, infrastructure, or performance

[echoix]

@nvuillam idea for improvement here: sort the required packages, to not have the order changed uselessly like here.

[nvuillam]

100% agreed, can be done in another PR :)

[echoix]

I think there's a bit of CI issues, in part with the new eslint release, so it might not get merged today, but I think it's good overall here ;)

[pjungermann]

I guess I cannot make lychee happy

  Errors in README.md
  ✗ [404] https://github.com/oxsecurity/megalinter/tree/main/docs/descriptors/api_spectral.md | Failed: Network error: Not Found
  ✗ [404] https://github.com/oxsecurity/megalinter/tree/main/docs/descriptors/api.md | Failed: Network error: Not Found

as these files don't exist at the main branch, yet.

[echoix]

However three tests for api spectral report failure : https://github.com/oxsecurity/megalinter/actions/runs/8694444485/job/23843361154#step:11:1

[nvuillam]

@pjungermann test classes are failing ^^

[echoix]

I won't merge now, since two issues on GitHub status makes the workflows on my other repo all fail since a couple hours. Now tests don't fail. The only error is the docs not yet published for the contents of this PR

[echoix]

In fact it will take @nvuillam to force the merge later on since it is required but fails.

[pjungermann]

Thank you!