fix: #3613614 Pass language parameters to oEmbed provider URLs

Stephen Mustgraverequested to merge
issue/drupal-3613614:3613614-oembed-iframe-pass into main

Adds lang attribute to oEmbed iframe wrapper (SC 3.1.1) and passes hl/locale parameters to YouTube/Vimeo oEmbed endpoints (SC 3.1.2).

  • Add preprocess_media_oembed_iframe hook to set langcode on
  • Add hook_oembed_resource_url_alter to pass hl (YouTube) and locale (Vimeo) parameters based on current content language
  • Include language in UrlResolver cache key for proper isolation
  • Add tests for language parameter behavior

Built on for #3593533.

Closes #3613614

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