[NewPM] Add pass options for `InternalizePass` to preserve GVs. (#91334)

This PR adds a string interface to `InternalizePass`' `MustPreserveGV`
option, which is a callback function to indicate if a GV is not to be
internalized. This is for use in LLVM.jl, the Julia wrapper for LLVM,
which uses the C API and is thus required to use the PassBuilder string
API for building NewPM pipelines.