[mlir] An implementation of dense data-flow analysis

This patch introduces an implementation of dense data-flow analysis. Dense
data-flow analysis attaches a lattice before and after the execution of every
operation. The lattice state is propagated across operations by a user-defined
transfer function. The state is joined across control-flow and callgraph edges.

Thge patch provides an example pass that uses both a dense and a sparse analysis
together.

Depends on D127139

Reviewed By: rriddle, phisiart

Differential Revision: https://reviews.llvm.org/D127173