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

[Aaron Ballman via cfe-commits]

AaronBallman wrote:

We talked about this at the Clang Language WG meeting and there were a lot of good arguments for either formatting/reorganizing as separate commits or for formatting/reorganizing in the same commit. If the folks doing a downstream pulldown are experienced with the code base, a single-step process is likely less disruptive. If the folks doing the pulldown are not experienced with the code base, a two-step process is likely less disruptive. (Nobody felt they had enough changes in Sema.h to block making sweeping changes to the file.)

I don't think we had strong consensus, but my read of the room was leaning more towards doing everything in one step.

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