Combine nav and navbar styles

- moves all the nav.less styling to navbar.less in the `client` directory
- deletes nav.less
- changes the nav.jsx import of styles to navbar.less
- stylelint navbar.less
- added a couple comments about easy future changes.

shared/naturalcrit/nav/nav.jsx

@@ -1,4 +1,4 @@
-require('./nav.less');
+require('client/homebrew/navbar/navbar.less');
 const React = require('react');
 const { useState, useRef, useEffect } = React;
 const createClass = require('create-react-class');