Split out `CodeGenTypes` from `CodeGen` for LLT/MVT

This reduces dependencies on `llvm-tblgen` so much.

`CodeGenTypes` depends on `Support` at the moment.
Be careful to append deps on this, since Targets' tablegens
depend on this.

Depends on D149024

Differential Revision: https://reviews.llvm.org/D148769

GitOrigin-RevId: 5d71ec6e448fa3ecb7e22368e97cf8274d5c84c6
89 files changed