Add Mobile Branding for Tor Browser

Currently when attempting to enable branding in the mozconfig with:

ac_add_options --with-branding=mobile/android/branding/torbrowser

the build throws an error. These branding files will need to be located and moved over to https://git.torproject.org/tor-browser.git

This bug deals with recent work regarding #25164 (moved)

0:12.52 ============================== 0:12.52 FATAL ERROR PROCESSING MOZBUILD FILE 0:12.52 ============================== 0:12.52 0:12.52 The error occurred while processing the following file: 0:12.52 0:12.52 /var/tmp/build/firefox-a0efd2fcd6e9/gfx/moz.build 0:12.52 0:12.52 The underlying problem is we referenced a path that does not exist. That path is: 0:12.52 0:12.52 /var/tmp/build/firefox-a0efd2fcd6e9/mobile/android/branding/torbrowser/moz.build 0:12.52 0:12.52 Either create the file if it needs to exist or do not reference it.