Splitting the cpp code generator out of the rest of the generators

[AsherGlick]

This probably should have been how it was done originally, but it was easier to just make the code generator a part of the existing generator. But now the generators are over a thousand lines long so lets just start splitting them out to better guarantee low coupling.

This is a big diff, but it is almost entirely copy/paste. The only times it is not copy paste is when we are removing the self variables, instead passing data in as an argument, and unindenting the code now that it is no longer a class method and just a normal function.

Functions that were more utility based functions and not directly tied to the cpp generator, maybe even needed for both generators, were moved to util.py so they could be included in both places at once.