Use the recently introduced transform dialect parameter mechanism to
perform controllable multi-size tiling with sizes computed at the
transformation time rather than at runtime.
This requires to generalize tile and split structured transform
operations to work with any transform dialect handle types, which is
desirable in itself to avoid unchecked overuse of PDL OperationType.
This almost looks like a transform dialect equivalent of OpFoldResult. If we had Values instead of Operation *. Maybe worth adding as a comment.