[X86] Add CPU detection for more znver2 CPUs (#74955)

This patch adds proper detection support for more znver2 CPUs.

Specifically, this adds in support for CPUs codenamed Renoir, Lucienne,
and Mendocino.

This was originally proposedfor Renoir in
https://reviews.llvm.org/D96220 and
got approved, but slipped through the cracks. However, there is still a
demand for this feature.

In addition to adding support for more znver2 CPUs, this patch also includes
some additional refactoring and comments related to cpu model
information for zen CPUs.

Fixes https://github.com/llvm/llvm-project/issues/74934.