User experience improvements

Summary:
This diff has some jak-shaving UX improvements after playing with the DataTable a bit more:

Selection
* deselecting a row from a larger set will make the last selected item the default selection
* re-selecting an item in a single selection will unselect it

Column Filtering
* Introduced button to toggle between filtering on all, nothing, and the values present in the current selection

Column sorting
* The up / down arrows are now inidividually clickable, rather than action as a general toggle
* Title still works as a general toggle between asc / desc / not sorted

Context menu
* I found the context menu for column selection and on the selected rows itself a bit finicky to find and click and not super intuitive for noob users. Merged both menus instead into a single hamburger menu adjacent to the search bar

Reviewed By: passy

Differential Revision: D26580038

fbshipit-source-id: 220f501a1d996acbd51088c08ea866caed768572

desktop/flipper-plugin/src/state/datasource/DataSource.tsx

@@ -299,6 +299,7 @@ export class DataSource<
   setReversed(reverse: boolean) {
     if (this.reverse !== reverse) {
       this.reverse = reverse;
+      // TODO: not needed anymore
       this.rebuildOutput();
     }
   }