[mlir][Affine] Add affine.delinearize_index operation

 This change adds a new AffineDelinearizeIndexOp to the affine dialect.
 The operation accepts an index type as well as a basis (array of index
 values) representing how the index should be decomposed into a
 multi-index. The decomposition obeys a canonical semantic that treats
 the final basis element as "fastest varying" and the first basis element
 as "slowest varying". A naive lowering of the operation using a sequence
 of AffineApplyOps is given.

RFC was discussed on discourse here: https://discourse.llvm.org/t/rfc-tensor-extracting-slices-from-tensor-collapse-shape/64034

Reviewed By: bondhugula, nicolasvasilache

Differential Revision: https://reviews.llvm.org/D131997