Feature: load_hints

[notlesh]

Problem: A program's hints need to be properly loaded using cairo-vm's extensive-hint feature and need to have their pc properly relocated.

Solution: Implement this logic during the load_program_hint using cairo-lang's def load_hints() as inspiration.

Note that this currently requires some trivial mods to cairo-vm (which I've done locally using a cargo patch) in order to make some items public.