Add pass to generate call graph .dot file

[stevenfontanella]

No description provided.

[kripken]

How does this compare to

https://github.com/WebAssembly/binaryen/blob/main/src/passes/PrintCallGraph.cpp

?

[stevenfontanella]

I didn't know we had that! It looks like that pass only creates edges for direct calls (there's some mention of indirect calls but it looks incomplete?). In this pass we include these three types of edges that aren't there in the existing pass, as well as nodes for function HeapTypes.

I find this pass useful, maybe I can merge that into the existing pass with an option to print different types of edges?

[kripken]

sgtm to improve the existing pass. Maybe even without a new flag, just add to it?