Relocate RelativeLink functionality to Firefox patch

We need to hardcode our home and profile settings from RelativeLink into a Firefox patch so that users still get expected behavior on Mac and Windows if they dock Firefox instead of the RelativeLink exe/containing app.

This will also prevent situations where TBB ends up set as the default browser or link handler, and gets launched to handle a url without RelativeLink.

This is a pretty bad usability bug, because Firefox will end up using the wrong profile if you launch it without RelativeLink right now.

In most cases, this will cause it to fail closed (because the socks proxy won't be listening), but not if the user already has proxy settings overrides for their default profile.