[clang] [clang-tools-extra] [clang] improve class type sugar preservation in pointers to members (PR #130537)

[Matheus Izvekov via cfe-commits]

mizvekov wrote:

> This patch ended up being pretty massive... ANYTHING we can do to reduce the size of this would be very appreciated.

It might be possible to split some stuff, but it would be hard to test it individually and avoid regressions in between the patches.

https://github.com/llvm/llvm-project/pull/130537