I'm working on more UNOPTFLAT fixes, but those require building a control flow graph for always blocks. AstWhile and AstJumpBlock are a bit of a pain. Can we simplify them along the following lines?

I noticed that the results for graph construction and flow searching differ significantly depending on the Java minor version being used. Specifically, when testing with JDK 21.0.6ga and JDK 21.0.7, ...