[5pt] graph-prototype: Add random-generated tests

[ivan-cukic]

Tests can never be extensive enough. Especially when asynchronous systems are tested.

A system that generates and tests random behaviors would allow us to test situations that we didn't manually write the tests for. Think of fuzzing, but with with more focus.

For example, system generates a random (to some extent) flow graph, and generates a random vector of tuples (delay, source_node, emit_value) which defines which source node sends which value at what point in time. The vector needs to be processed without GP to see what is the expected output of said graph. The result of non-GP processing needs to be the same as the result we get from running the flow graph with GP.