[clang] [llvm] wip: Move instrumentation passes (PR #92171)

[Arthur Eubanks via llvm-commits]

https://github.com/aeubanks commented:

looks pretty good to me

for testing the pre-inliner one, we should add some tests in `llvm/test/Transforms/EntryExitInstrumenter/` that invoke things like `opt -passes='default<O1>'`, `opt -passes='thinlto-pre-link<O2>'`, `opt -passes='thinlto<O3>'` to make sure that the pass did/didn't insert the call given some IR with the appropriate function attribute

for testing the post-inliner one, an `llc` x86-64 test that checks that a call to the function was generated in the assembly given some IR with the appropriate function attribute is enough

https://github.com/llvm/llvm-project/pull/92171