[BE] Support request to search REST api endpoint with a granular PAT

/search REST API endpoint - Depending on the scope param - we return different (and multiple) objects - similar to a graphQL query

Code class - currently supports legacy PATs with the following scopes?

• :api - Full API access
• :read_api - Read-only API access (sufficient for search)
• :ai_workflows - AI workflow access (allows GET/HEAD search requests)

Related: Ayush's dev guidelines and Alex's handbook