Always display tab navigation on local/federated timeline even when empty (#7663)

Fix #7659

app/javascript/mastodon/features/community_timeline/index.js

@@ -127,6 +127,7 @@ export default class CommunityTimeline extends React.PureComponent {
 
         <StatusListContainer
           prepend={headline}
+          alwaysPrepend
           trackScroll={!pinned}
           scrollKey={`community_timeline-${columnId}`}
           timelineId={`community${onlyMedia ? ':media' : ''}`}

app/javascript/mastodon/features/public_timeline/index.js

@@ -127,6 +127,7 @@ export default class PublicTimeline extends React.PureComponent {
 
         <StatusListContainer
           prepend={headline}
+          alwaysPrepend
           timelineId={`public${onlyMedia ? ':media' : ''}`}
           onLoadMore={this.handleLoadMore}
           trackScroll={!pinned}