Add SparseConstantPropagation to the data flow solver demo

[j2kun]

See https://discourse.llvm.org/t/mlir-dead-code-analysis/67568/8

I tried out the data flow analysis framework, and also realized the DeadCodeAnalysis was required for pretty much every analysis I wanted to do. So I’m sympathetic to making this easier to get started with, but I’m also curious what making it a “built-in” feature would entail. Maybe rather than built-in in the sense of “always included in DataFlowSolver” is too strong, but we could provide some helper that includes some sensible defaults (e.g. DeadCodeAnalysis and SparseConstantPropagation), which users could extend.

Otherwise it won't properly handle control flow, which I didn't test enough in my tutorial, but ran into when I was working on this in HEIR.