[mlir] Support inlining into affine operations

Introduce support for inlining into affine operations. This uses the generic
inline infrastructure and boils down to checking that, if applied, the inlining
doesn't violate the affine dimension/symbol value categorization. Given valid
IR, only the values that are valid dimensions/symbols thanks to being top-level
in their affine scope need special handling.

Reviewed By: rriddle

Differential Revision: https://reviews.llvm.org/D92770