[clang-tools-extra] [clang-tidy] Add new check 'misc-scope-reduction' (PR #175429)

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vabridgers wrote:

> We should not post (probably unreviewed) AI text, https://llvm.org/docs/AIToolPolicy.html

Are you referring to the formatted comment about how the work was done and status? Shall I delete the comment?

https://github.com/llvm/llvm-project/pull/175429