[mlir][Vector] Support broadcast vector type in distribution of vector.warp_execute_on_lane_0.

This revision significantly improves and tests the broadcast behavior of vector.warp_execute_on_lane_0.

Previously, the implementation of the broadcast behavior of vector.warp_execute_on_lane_0
assumed that the broadcasted value was always of scalar type.

This is not necessarily the case.

Differential Revision: https://reviews.llvm.org/D133767