[clang-tools-extra] [clang-tidy] add depercation warning for non-whitelisted global options (PR #121057)

[Julian Schmidt via cfe-commits]

https://github.com/5chmidti approved this pull request.

Looks good from my side.

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> Perhaps we can just land this as is for now and introduce the escape hatch if we get feedback indicating it's needed?

I think that is totally fine. If this comes up, we can also immediately backport the flag so that users don't have to wait, e.g., months for their distro (etc.) to update the major version.

https://github.com/llvm/llvm-project/pull/121057