database: User added private repos should be listed

Created by: ryanslade

Our permissions system was not taking into account private repos added via code host connections, not sign in connections.

This fix is a workaround that assumes any code added by a user added external service should be visible by the user who owns the external service. The assumption is that if they had access to sync the repo, they should have access to read it. This approach side steps our existing permissions syncing system and so is not an ideal long term solution but is quick to implement.

Closes: https://github.com/sourcegraph/sourcegraph/issues/20262