disasm: Guess function arguments

[shazow]

... without just looking up the sighash on a 4byte database. 😅

I don't have a great idea of how to do this without symbolic execution. I'd like to keep whatsabi to static analysis in O(nlogn) runtime per number of instructions.

My gut feel is that the process to approach this:

1. Try to guess the total expected calldata size, or even number of arguments
2. Might help if we can figure out the bytecode boundaries for each function? (are JUMPI table to JUMPDEST mappings contiguous?)
3. Figure out the expected byte size of each argument, if any?

I think that's as far as we can get without tracking a non-fixed stack depth.

Related project: ethb3rlin/find-a-team#32