[mlir:PDL] Add support for creating ranges in rewrites

This commit adds support for building a concatenated range from
a given set of elements, either single element or other ranges, within a
rewrite. We could conceptually extend this to support constraining
input ranges, but the logic there is quite a bit more complex so it is
left for later work when a need arises.

Differential Revision: https://reviews.llvm.org/D133719