[mlir][Linalg] Add utility method to reshape ops to express output shape in terms...

[mlir][Linalg] Add utility method to reshape ops to express output shape in terms of input shape.

Resolving the dim of outputs of a tensor_reshape op in terms of its
input shape allows the op to be eliminated when its used only in its
dims. The init_tensor -> tensor_reshape canonicalization can be
simplified to use the dims of the output of the tensor_reshape which
gets canonicalized away later making the tensor_reshape dead.

Differential Revision: https://reviews.llvm.org/D96635