Generated API references from OpenAPI file

[curquiza]

✅ Needs meilisearch/meilisearch#6145 to be merged

Docs

• Use openAPI file to generate API reference
• Split API reference Overview page into sub pages, still uder API reference group
• Github -> GitHub
• Add missing code sample for /indexes/uid/fields route

Internal tooling and CIs

• Improve Post deployment CI to trigger and generate OpenAPI files (+ creation of the scripts)
• Add CI to check code samples in open API file (+ creation of the scripts)
• Add PR template to ensure we do not miss steps related to code samples
• Add scripts to npm commands, and so use npm run instead of directly the scripts in CIs

Summary by CodeRabbit

• Documentation
  • Restructured API Reference navigation and redirects; added Authorization, Headers, Pagination, Requests, and OpenAPI pages.
  • Added API playground config and an "API Routes" group with example language support.
  • Updated many internal doc links, elevated error-code headings for clearer navigation, fixed branding to "GitHub", and added analytics event field "userId".
  • Added extra code-sample examples for federated multi-search fields.
• Chores
  • New PR template and CI/workflow/tooling updates to improve OpenAPI and code-sample generation and validation.