[clang] [clang][NFC] Regroup declarations in `Sema` (PR #82217)

[Younan Zhang via cfe-commits]

zyn0217 wrote:

> That's because you are filtering only opened PRs, not including drafts PRs. For example there is this draft PR: https://github.com/llvm/llvm-project/pull/81095/files

(I think my recent PR https://github.com/llvm/llvm-project/pull/82310 now supersedes my two draft PRs, and they can be closed now.)

https://github.com/llvm/llvm-project/pull/82217