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.