dunfell-clang14: Update from clang 12 to clang 14

[rakuco]

This gigantic pull request contains a lot of cherry-picks from the kirkstone branch that move clang from version 12 to version 14. This is necessary to update Chromium beyond M114 in meta-chromium, as clang 12 is too old for the language features used by Chromium.

This has been compiled and runtime-tested as described in https://github.com/OSSystems/meta-browser/issues/734#issuecomment-1661928446 and subsequent comments.

Parts of the changes had already landed separately in the dunfell-clang12 branch, so I did have to manually fix some conflicts in some LLVM update cherry-picks.

I've specifically skipped some commits touching recipes that are not used by Chromium, such as the bpf, bcc and android-tools commits, and OTOH it's also possible that I've cherry-picked too many changes, some of which can be dropped.

Fixes #835.

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[rakuco]

Thanks for the quick review, @kraj!

[kraj]

Thanks for the quick review, @kraj!

I have already looked at it last week in your tree after you emailed me, so I was just waiting for the PR