Use type hints to resolve method calls within a scope

[BPHarris]

Ratter currently supports class initialisers and static methods, however, it does not support standard methods as the type of the method owner is unknown.

While static typing is out-of-scope, within a fixed scope (function, etc) Ratter could take type hints as always true and resolve the method called that way. Though this does introduce potential issues when the type hints are incorrect -- either producing the wrong results with no warning or attempting to resolve a non-existent method.

Furthermore, as a part of the MR, there should be the ability to resolve self types.