Add /api/v1/content/_refresh endpoint for cache and index refresh

[dsolistorres]

Closes #33587

Proposed Changes

• This PR introduces a new REST endpoint (/api/v1/content/_refresh) that allows manual refresh of a contentlet in the cache and the search index. This is particularly useful for troubleshooting cache-related issues and forcing content reindexing.
• A postman test has been included to verify the new endpoint.

Checklist

• Tests