Use latest base config

[aaronmars]

In addition to updating to the latest base config, also:

• Add a rule to enforce that functional components are only implemented as arrow functions
• Allow for static class variables in the react/sort-comp rule

[JeremyRH]

Add a rule to enforce that functional components are only implemented as arrow functions

Does that mean we can't do this?

export default function Component() {...

[aaronmars]

After some discussion, I'll turn "off" the arrow function enforcement and leave that decision to the end users to turn on or off.