[iOS GPU][BE][2/n] Remove unused APIs (#60281)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/60281
1. REmove unused APIs from MPSImageUtils.
2. Move tensor related APIs from MetalUtils to MetalTensorUtils. Delete MetalUtils.h/mm
3. Move metal buffer related APIs to MetalContext
ghstack-source-id: 131839559
Test Plan:
1. CircleCI
2. buck test pp-mac
Reviewed By: SS-JIA
Differential Revision: D29232973
fbshipit-source-id: a4c0c848883b8ef615eeb2936c1f3d18cddcb318
