[mlir][Linalg] Allow distribution `scf.parallel` loops generated in

[mlir][Linalg] Allow distribution `scf.parallel` loops generated in
Linalg to processors.

This changes adds infrastructure to distribute the loops generated in
Linalg to processors at the time of generation. This addresses use
case where the instantiation of loop is done just to distribute
them. The option to distribute is added to TilingOptions for now and
will allow specifying the distribution as a transformation option,
just like tiling and promotion are specified as options.

Differential Revision: https://reviews.llvm.org/D85147