Opengrok To Search WithIn the returned results

[sailukar]

Is your feature request related to a problem? Please describe.
Currently it is not possible to search for a string within the results.

Describe the solution you'd like
Opengrok should provide an option to search with in the results returned by the previous search.
This can greatly improve to narrow down the results with the query strings.

Describe alternatives you've considered
No

Additional context
We can have few options to search with in the result files like
Search within the Lines matched Previously
Search with in the Files matched Previously.