[mlir][linalg] Add unsigned min/max/cast function to OpDSL.

Update OpDSL to support unsigned integers by adding unsigned min/max/cast signatures. Add tests in OpDSL and on the C++ side to verify the proper signed and unsigned operations are emitted.

The patch addresses an issue brought up in https://reviews.llvm.org/D111170.

Reviewed By: rsuderman

Differential Revision: https://reviews.llvm.org/D111230