Refactor: python: Simplify pattern class instantiation.

• Add an all to patterns.py to control what gets exported. Turns out it's really only one class we care about.

• Inheriting from object is no longer necessary.

• Rename patternvariants to patternVariants and statically declare its contents instead of constructing them at runtime. We really only support a single variant, so the extra complication is not necessary.

• Rename crm_corosync to Corosync2Patterns and have PatternSelector directly instantiate it instead of instantiating BasePatterns and then through some weird side-effect action call it to set up all the subclass stuff.

• Stop passing the variant name into all the Corosync2Pattern methods. We already know the name - it's part of the object from when we instantiated it. This then allows getting rid of the get_variant method.

• Fix up all the users to no longer pass the variant name, either.