[nnc] Support `pow` on CPU (#56308)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/56308
But only for float tensors. Even on CUDA, int tensors just have weird
behavior with pow, and I bet FP is so much more common that it's just not worth
trying to fuse ints here.
ghstack-source-id: 126769637
Test Plan: `pytest test_jit_fuser_te.py -k test_binary_pow`
Reviewed By: navahgar
Differential Revision: D27834694
fbshipit-source-id: 7274d72cf02ab95d63574b6c17995b8f34560810
