[llvm] [AMDGPU] Move AMDGPUTargetMachine into AMDGPUCodeGenPassBuilder(NFC) (PR #103720)

[Christudasan Devadasan via llvm-commits]

cdevadas wrote:

> Should only move TargetPassConfig. TargetMachine should stay in TargetMachine files. Failing that, I would rather merge CodeGenPassBuilder into the TM files

Certain options and static declarations are used between TM and TargetPassConfig. So moving CodeGenPassBuilder into AMDGPU TM is the viable option to avoid extern declarations of various common options.

https://github.com/llvm/llvm-project/pull/103720