[SLP][REVEC] Make SLP vectorize shufflevector. (#102489)

Add getShufflevectorNumGroups to vectorize shufflevector.

Current getShufflevectorNumGroups can only vectorize limited pattern
(e.g., the masks of shufflevector use the elements of the source in
order).

In addition, ReuseShuffleIndices and ReorderIndices are not supported.

Author: HanKuanChen