This revision completes the "dimension ordering" feature
of sparse tensor types that enables the programmer to
define a preferred order on dimension access (other than
the default left-to-right order). This enables e.g. selection
of column-major over row-major storage for sparse matrices,
but generalized to any rank, as in:
dimOrdering = affine_map<(i,j,k,l,m,n,o,p) -> (p,o,j,k,i,l,m,n)>
Reviewed By: bixia
Differential Revision: https://reviews.llvm.org/D102856
