Onboarding & feed fixes (#1602)

* Fix: improve the 'end of feed' detection condition

* Fix the feeds link on mobile in the empty state

* Align the following empty state better on web

* Dont autofocus the search input in the search tab

* Fix the error boundary render

* Add 'end of feed' CTA to following feed

* Reduce the default feeds to discover now that we have feed-selection during onboarding

* Fix case where loading spinner fails to stop rendering in bottom of feed

* Fix: dont show loading spinner at footer of feed when refreshing

* Fix: dont fire reminders during onboarding

* Optimize adding feeds and update to mirror the api behaviors more closely

* Use the lock in preferences to avoid clobbering in-flight updates

* Refresh the feed after onboarding to ensure content is visible

* Remove the now-incorrect comment

* Tune copy

src/view/com/util/ErrorBoundary.tsx

@@ -28,7 +28,7 @@ export class ErrorBoundary extends Component<Props, State> {
   public render() {
     if (this.state.hasError) {
       return (
-        <CenteredView>
+        <CenteredView style={{height: '100%', flex: 1}}>
           <ErrorScreen
             title="Oh no!"
             message="There was an unexpected issue in the application. Please let us know if this happened to you!"