feat(docs-infra): Add opensearch description (#25479)

Enables Chrome users to search angular.io and its subdomains from the browsers navigation bar.
Not sure if compatible with Firefox yet.
The queried term in the URL is removed after closing the search-results.

PR Close #25479

aio/scripts/deploy-to-firebase.sh

@@ -92,6 +92,10 @@ fi
   # Include any mode-specific files
   cp -rf src/extra-files/$deployEnv/. dist/
 
+  # Set deployedUrl as parameter in the opensearch description
+  # deployedUrl must end with /
+  yarn set-opensearch-url $deployedUrl
+
   # Check payload size
   yarn payload-size