[mlir][vector] generalized masked l/s and compressed l/s with indices

Adding the ability to index the base address brings these operations closer
to the transfer read and write semantics (with lowering advantages), ensures
more consistent use in vector MLIR code (easier to read), and reduces the
amount of code duplication to lower memrefs into base addresses considerably
(making codegen less error-prone).

Reviewed By: ThomasRaoux

Differential Revision: https://reviews.llvm.org/D94278