[MPS] Enable `bfloat16` support on MacOS 14 (#119641)
Per [MPSDataType](https://developer.apple.com/documentation/metalperformanceshaders/mpsdatatype/mpsdatatypebfloat16?changes=_11&language=objc) documentation bfloat16 are supported in MacOS Sonoma or later
Added missing `MPSDataTypeBFloat16` and `MTLLanguageVersion3_1` enums to `MPSGraphSonomaOps.h`
TODO: Enable more testing
Pull Request resolved: https://github.com/pytorch/pytorch/pull/119641
Approved by: https://github.com/Skylion007
