[clang] [Clang] Replace vt_gen with LLVMCodeGenTypes (PR #109601)

[Tristan Ross via cfe-commits]

RossComputerGuy wrote:

You're welcome, though it looks like CI is borked.
```
ld.lld: error: unable to find library -lLLVMLLVMCodeGenTypes
clang: error: linker command failed with exit code 1 (use -v to see invocation)
```
I've changed it from `LLVMCodeGenTypes` to `CodeGenTypes` so hopefully CI passes now.

https://github.com/llvm/llvm-project/pull/109601