[llvm] [NewPM][BPF] Add BPFPassRegistry.def NFCI (PR #86241)

[Arthur Eubanks via llvm-commits]

aeubanks wrote:

in general porting all these backends at once makes me nervous that it'll be harder to make large changes to the new PM for codegen. I'd prefer if we first focused on making one backend work end to end, plus getting various necessary infra changes like https://github.com/llvm/llvm-project/issues/84397

https://github.com/llvm/llvm-project/pull/86241