Remove deprecated non string API for LLVM pass pipeline and parse all options (#55407)
This technically removes the option for Oz in julia but it doesn't
actually do what one wants.
This removes an API currently used by Enzyme.jl and AllocCheck.jl but
given that LLVM.jl doesn't support this API anymore that seems fine.
@wsmoses @maleadt
Do we want the replacement for this (a function that parses the
PipelineConfig struct) to live in LLVM.jl or GPUCompiler.jl ?