[MPS] Add APIs to query current and driver allocated memory in MPSAllocator (#94649)
- Fixed the formatting in MPSAllocator.mm
- Added `getCurrentAllocatedMemory()`and `getDriverAllocatedMemory()` to query memory allocations required for Memory Leak Detection in test_mps.py
Pull Request resolved: https://github.com/pytorch/pytorch/pull/94649
Approved by: https://github.com/DenisVieriu97, https://github.com/kulinseth
