insights: add sub-repo permissions checker to code-insights worker

Created by: sashaostrikov

As an initial implementation, sub-repo permissions are checked for every repo in search results of code insights search query. No caching (per repoID) is happening currently.

If repo supports sub-repo permissions, then search result related to this repo is excluded and the data point of this repo is dropped

Closes https://github.com/sourcegraph/sourcegraph/issues/27490

Test plan

I wrote unit tests for code-insights worker layer and database layer.