[NFC] Refactor how CFI section types are represented in AsmPrinter

In terms of readability, the `enum CFIMoveType` didn't better document what it
intends to convey i.e. the type of CFI section that gets emitted.

Reviewed By: dblaikie, MaskRay

Differential Revision: https://reviews.llvm.org/D76519

GitOrigin-RevId: 63cfab4f40390bf10a313039adf0b955db9706b9
5 files changed