Switch out flake8 for pylint in GH actions, add pytype

[alejandroschuler]

Good linting and type annotations can catch a lot of bugs even without unit tests. We should use pylint and pytype in our continuous integration workflow to do this.

[alejandroschuler]

This will also involve adding type annotations and documentation to the internals of the codebase.

[ryan-wolbeck]

@alejandroschuler I've been thinking about this some more and I'm thinking about adding in pre-commit hooks to setup a lot of the formatting related stuff. I'm also a fan of flake8 when used properly, one reason is that pylint will throw a ton of errors on this project because classes have too many inputs and would create some pretty tedious re-writes, without a ton of real value imo.