Add support for LLVM 22

[nathanchance]

• Update LLVM main anchor and version to 23 (pull request)
• Wait for LLVM 22 binaries on kernel.org
• Wait for TuxMake to provide korg-clang-22 images
• Wait for TuxSuite to allow korg-clang-22 to be specified
• Update generator/yml to provide llvm_21 anchor and copy all llvm_latest builds to it
• Update generator/yml to shift llvm_latest to 22 and copy all llvm_tot builds to it