[mlir][linalg] Always generate an extract/insert slice pair when tiling output tensors.

Adapt tiling to always generate an extract/insert slice pair for output tensors even if the tensor is not tiled. Having an explicit extract/insert slice pair simplifies followup transformations such as padding and bufferization. In particular, it makes read and written iteration argument slices explicit.

Depends On D114067

Reviewed By: nicolasvasilache

Differential Revision: https://reviews.llvm.org/D114085