DML EP add einsum MatMul NHCW ops (#13440)
### Description
This adds the "NHCW" format support for einsum MatMul. The logic is
basically a merge of the existing Transpose and MatMul Einsum
implementations.
### Motivation and Context
Some transformer models that I'm tracking use Einsum quite often during
a single inference, and about half of those were "NHCW" MatMul Einsums.
Supporting them will reduce the number of copies to the CPU.
