feat: implement JSDoc-based documentation validation and automated MDX generation workflow

[max-ostapenko]

This pull request introduces automated workflows and supporting scripts for validating and syncing JSDoc-based documentation with code. The primary focus is on ensuring documentation parity and providing a mechanism to generate and synchronize documentation with the har.fyi repository.

Example of the validated and generated docs: HTTPArchive/har.fyi#167

GitHub Actions Workflows:

• Added a new workflow .github/workflows/docs.yml to validate JSDoc comments against code and automatically sync generated documentation to the har.fyi repository via a pull request. This workflow runs on pushes, pull requests, and can be triggered manually.
• Updated .github/workflows/linter.yml to include a new validate-docs job that runs the documentation validation as part of the CI process.

Documentation Scripts and Tooling:

• Added new npm scripts validate:docs and generate:docs in package.json to run documentation validation and generation tools.

[tunetheweb]

Looks mostly OK to me but have some comments.

My two main concerns would be:

1. Will this make it less likely for contributors to want to edit custom metrics? Probably not?
2. You're planning on migrating har.fyi to httparchive.org so if this the right time to introduce this?

[max-ostapenko]

1. Will this make it less likely for contributors to want to edit custom metrics? Probably not?

That's why I decided to keep the code as-is, just require comments.
We can add a quick guide on JSDoc if there will be questions. But I hope by expanding it to other metrics will give plenty of examples.

2. You're planning on migrating har.fyi to httparchive.org so if this the right time to introduce this?

Switching to another destination repo is not a big effort.

[github-actions]

https://almanac.httparchive.org/en/2022/

WPT result details

Changed custom metrics values:

{
  "_ads": {
    "ads": {
      "present": false,
      "status": 404,
      "redirected": true
    },
    "app_ads": {
      "present": false,
      "status": 404,
      "redirected": true
    },
    "sellers": {
      "present": false,
      "redirected": true,
      "status": 404
    }
  },
  "_privacy": {
    "iab_tcf_v1": {
      "present": false
    },
    "iab_tcf_v2": {
      "present": false
    },
    "iab_gpp": {
      "present": false
    },
    "iab_usp": {
      "present": false
    },
    "navigator_doNotTrack": false,
    "navigator_globalPrivacyControl": true,
    "document_permissionsPolicy": false,
    "document_featurePolicy": true,
    "referrerPolicy": {
      "entire_document_policy": null,
      "individual_requests": null,
      "link_relations": null
    },
    "request_hostnames_with_cname": {},
    "ccpa_link": {
      "hasCCPALink": false
    },
    "iab_ddr": {
      "present": false,
      "status": 404
    }
  }
}