[new] add static-property-placement rule

[dmason30]

This adds a rule discussed in these two issues:

• Fixes Add rule to require static propTypes = .. instad of Foo.propTypes = .. for class-based components #1923
• Fixes Experimental features? #1807

I have based the options on @ljharb suggestions from both issues. This is my first attempt at writing a rule so I expect plenty of feedback.

• static public field (ClassProperty)
• static getter {MethodDefinition)
• property assignment (MemberExpression)

...
"react/static-property-placement": [<enabled>, <string>, {
  childContextTypes: <string>,
  contextTypes: <string>,
  contextType: <string>,
  defaultProps: <string>,
  displayName: <string>,
  propTypes: <string>,
}]
...

• Also I have never worked with TypeScript/Flow so I am not sure what (if any) additional changes are needed?

• This rule only applies to ES6 classes.
  -- Ignored: Stateless functional components can only ever have a MemberExpression to declare any of the above properties.
  -- Ignored: The React.createClass/createReactClass can only ever have a Property to declare any of the above properties.

• This does not have autofix either but I feel that is a "nice to have" option and could come later.

[ljharb]

I'd also like this form to be incorrect code:

class Foo extends React.Component {
  static get defaultProps() {}
}

So perhaps we need a third option, static getters?

[dmason30]

Added the static getter option - Great Idea 🎉

I await your feedback.

[dmason30]

@ljharb LGTM?