Patch Re-Order an base-browser'ification of Tor Browser for Android

Separate Android portion of #41807 (closed)

This will probably go to @clairehurst next spring, @pierov will be a useful resource there (feel free to edit this description to be more accurate 😄)

The high-level idea is to orer/organize the firefox-android patchset in this relative order:

firefox-android upstream
security backports
security patches
privacy patches
new non-tor specific functionality (eg security level)
base-browser
tor integration
further tor-specific/dependent features
tor-browser HEAD

Long term we should be able to build base-browser from firefox-android which references tor-browser/geckoview base-browser from which we can base mullvad-browser for Android (hi @ruihildt 👋)

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