[MPS] Add equal operator (#80195)
Which is, in essence is composite of `eq`->`all`->`item`
`native/mps/operators/Equal.cpp` is an almost verbatim copy of `native/cuda/Equal.cpp`
Fix codegen by generating MPSFunctions headers
Pull Request resolved: https://github.com/pytorch/pytorch/pull/80195
Approved by: https://github.com/albanD
