[mlir][vector] Add patterns to cast away leading 1-dim

[mlir][vector] Add patterns to cast away leading 1-dim

This patch adds patterns to use vector.shape_cast to cast
away leading 1-dimensions from a few vector operations.
It allows exposing more canonical forms of vector.transfer_read,
vector.transfer_write, vector_extract_strided_slice, and
vector.insert_strided_slice. With this, we can have more
opportunity to cancelling extract/insert ops or forwarding
write/read ops.

Reviewed By: ThomasRaoux

Differential Revision: https://reviews.llvm.org/D95873