[lld] [lld] Change `--lto-emit-llvm` to use the pre-codegen module (PR #97480)

[Fangrui Song via llvm-commits]

MaskRay wrote:

`PreCodeGenModuleHook` makes sense as that is similar to clang cc1 `-emit-llvm`  and `-emit-llvm-bc` for ThinLTO backend compiles.

https://github.com/llvm/llvm-project/pull/97480