Firefox extension should ask for limited URL access

Created by: christinaforney

The Firefox chrome extension currently asks for access to all websites. It should be updated to ask for the same limited set of sites that the Chrome extension asks for.

https://sourcegraph.com/github.com/sourcegraph/sourcegraph@4d84cd2b62888f584c514e67e46119dff43a3049/-/blob/browser/scripts/tasks.ts#L84:31

We originally wanted to use limited access but because of https://bugzilla.mozilla.org/show_bug.cgi?format=default&id=1382953 it made the on-boarding flow really terrible for users. This issue is fixed so we can revisit.