fix: Keyboard accessible context menus (#1768)

- Makes menus fully accessible and keyboard driven
- Currently adds 2.8% to initial bundle size due to the inclusion of Reakit and its dependency, popperjs.
- Converts all menus to functional components
- Remove old custom menu system
- Various layout and flow improvements around the menus

closes #1766

app/components/Actions.js

@@ -11,11 +11,6 @@ export const Action = styled(Flex)`
   font-size: 15px;
   flex-shrink: 0;
 
-  a {
-    color: ${(props) => props.theme.text};
-    height: 24px;
-  }
-
   &:empty {
     display: none;
   }