[MLIR][XeGPU] Add blocking and subgroup to lane distribution support for ConvertLayout operation (#183837)

This PR refactors blocking support for ConvertLayout op to allow it
unrollable, not just removing it for specialize case.
It also removes the foldable attribute for ConvertLayout op, as we
expect the OP to be explicitly handled by XeGPU lowering.
It adds subgroup to lane distribution support for ConvertLayout op.

GitOrigin-RevId: 3b4d5ffe847ce194173c3b778a34e55d416e6544