liveness analysis

[Roger-luo]

implement a new liveness analysis using the interpreter framework to test if all the abstraction works well backwards, similar to constprop, we will create this in a separate crate kirin-liveness, once we have this implemented, we should be relatively converged on the abstract interpreter framework.

[Roger-luo]

we are gonna merge #677 and #682 first there are some remaining small issues to solve

• rename Region -> CFG given now this is kinda specific to CFG
• investigate why interpreter framework is specialized to Region, it should be generic to bodies like Block, DiGraph, UnGraph, a good way to exam this is test it on a toy langauge that combines a computational graph in DiGraph with a regular SSA IR (e.g the arith + cf + function region)
• simplify the boilerplate in toy-lang, right now sparse liveness is only useful for validating the IR, if IR is validate the usedef chain is already in the IR attached to each SSAValue, no need to rerun the analysis before dense liveness