Moved fetching site data to first load of search popup

refs https://github.com/TryGhost/Team/issues/1665

- previously the search was loading site data on load for indexing, which adds unnecessary load if search is not used
- moves data fetch and indexing to when the search popup is opened first time avoiding unnecessary fetch

ghost/sodo-search/src/App.js

@@ -15,16 +15,14 @@ export default class App extends React.Component {
 
         this.state = {
             searchIndex,
-            showPopup: false
+            showPopup: false,
+            indexStarted: false,
+            indexComplete: false
         };
     }
 
-    async componentDidMount() {
+    componentDidMount() {
         this.initSetup();
-        await this.state.searchIndex.init();
-        this.setState({
-            indexComplete: true
-        });
     }
 
     componentDidUpdate(_prevProps, _prevState) {
@@ -33,6 +31,20 @@ export default class App extends React.Component {
                 searchValue: ''
             });
         }
+
+        if (this.state.showPopup && !this.state.indexStarted) {
+            this.setupSearchIndex();
+        }
+    }
+
+    async setupSearchIndex() {
+        this.setState({
+            indexStarted: true
+        });
+        await this.state.searchIndex.init();
+        this.setState({
+            indexComplete: true
+        });
     }
 
     componentWillUnmount() {

ghost/sodo-search/src/AppContext.js

@@ -9,7 +9,10 @@ const AppContext = React.createContext({
     lastPage: '',
     page: '',
     pageData: {},
-    dispatch: (_action, _data) => {}
+    dispatch: (_action, _data) => {},
+    searchIndex: null,
+    indexComplete: false,
+    searchValue: ''
 });
 
 export default AppContext;