Custom button for expand/collapse node in Tree

Summary: When clicking a node in the tree, currently it expands or collapses the subtree under it. This adds a chevron button which only handles the expansion functionality, and clicking on the label with the Section name will show info about that Section in the side panel.

Reviewed By: fabiomassimo

Differential Revision: D17165150

fbshipit-source-id: ac6b6c127b68274f53523b3ea62422ff96116e9b

src/plugins/sections/index.js

@@ -172,8 +172,10 @@ export default class extends FlipperPlugin<State, *, PersistedState> {
 
   onNodeClicked = (targetNode: any, evt: InputEvent) => {
     if (targetNode.attributes.isSection) {
+      const sectionData = {};
+      sectionData['global_key'] = targetNode.attributes.identifier;
       this.setState({
-        selectedTreeNode: null,
+        selectedTreeNode: {sectionData},
       });
       return;
     }