[mlir] Fix masked vector transfer ops with broadcasts

Broadcast dimensions of a vector transfer op have no corresponding dimension in the mask vector. E.g., a 2-D TransferReadOp, where one dimension is a broadcast, can have a 1-D `mask` attribute.

This commit also adds a few additional transfer op integration tests for various combinations of broadcasts, masking, dim transposes, etc.

Differential Revision: https://reviews.llvm.org/D101745