[mlir][Linalg] Replace SimplePad with PadTensor in tile-and-pad

This revision creates a build method of PadTensorOp which can be mapped to
SimplePad op. The verifier is updated to accept a static custom result type,
which has the same semantic as SimplePadOp.

Reviewed By: nicolasvasilache

Differential Revision: https://reviews.llvm.org/D95555