Fix splash screen branding and other issues in RR

🐞 Bug Report

There were a few instances of firefox branding that were noticed after the 148 rebase (but could have showed up in an earlier RR). Specifically:

  1. The splash screen
  2. The custom icons
  3. Some minor places, like the tab favicon for about:home

image.png image image

User impact

High, user will see moz branding instead of our own

Bookkeeping

  • Browser version:
  • Browser channel:
    • Release
    • Alpha
    • Nightly
  • Distribution method:
    • Installer/archive from torproject.org
    • tor-browser-launcher
    • homebrew
    • other (please specify):
  • Operating System:
    • Windows
      • Version:
    • macOS
      • Version:
    • Linux
      • Distribution + Version:
      • Desktop Environment + Version:
    • Android
      • Version:
      • Device:
    • Tails
    • Other (please specify):

Does this bug occur in a fresh installation?

Yes

Edited by clairehurst