We adapt the download path, too, to the one Mozilla is using.

Bump clang to final 11.0.0 commit and cbindgen to 0.15.0.

Use build-tools and platform-tools 29.0.2 now to align GeckoView
and android-components/fenix toolchains better.

This bumps the checkpoint to height 518353.

The patch was removed as an input file during the release prep version
bump.

Versions bump and Changelog update

Remove firefox-locale-bundle and remaining mobile bits in the firefox
project.

Update fenix

Update documentation on how to fetch Gradle dependencies

Update android-components

We additionally clean up our build script so that we actually only
compile the browser engine code we want to be compiled (the build
breaks otherwise due to GeckoView mismatch which caused us to exempt
geckoview-nightly from getting overwritten by our own earlier on).

Update application-services

This reverts commit 82ad6be5.

We need to bump Rust to 1.45 for #40115 and thus, we need to back out
this patch again and try finding a fix for #40114 instead.

Update GeckoView part