Tor Launcher button labels are missing (Firefox 76)

When running inside a Tor Browser that is based on Firefox 76 or newer, some button labels are missing from Tor Launcher's setup wizard. To fix this, we need to apply the same workaround as Mozilla applied in https://bugzilla.mozilla.org/show_bug.cgi?id=1625938

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information