[torconnect] Combine "Connection Assist" and "Location Settings" into a single tab

In the usability testing @nah conducted in tpo/ux/research#52 (closed), only one user realized Tor Browser was using their location when attempting to try a bridge. To ensure we get informed consent for this feature and bring the location UI forward we've combined the Connection Assist and Location Settings tabs into one:

Given that change, we'll also need to incorporate and default to the "Automatic" option that's currently present in Connection Settings (see #40782 (comment 2771120) for reference).

And provide a dedicated error screen for when autolocate fails: