[mlir][vector] Generalize vector.transpose lowering to n-D vectors

The existing vector.transpose lowering patterns only triggers if the
input vector is 2D. The revision extends the pattern to handle n-D
vectors which are effectively 2-D vectors (e.g., vector<1x4x1x8x1).

It refactors a common check about 2-D vectors from X86Vector
lowering to VectorUtils.h so it can be reused by both sides.

Reviewed By: dcaballe

Differential Revision: https://reviews.llvm.org/D149908