Add useHashtagStream hook, clean up hashtags timeline (remove unused code for fetching multiple hashtags)

app/soapbox/api/hooks/index.ts

@@ -49,6 +49,7 @@ export { useUserStream } from './streaming/useUserStream';
 export { useCommunityStream } from './streaming/useCommunityStream';
 export { usePublicStream } from './streaming/usePublicStream';
 export { useDirectStream } from './streaming/useDirectStream';
+export { useHashtagStream } from './streaming/useHashtagStream';
 export { useListStream } from './streaming/useListStream';
 export { useGroupStream } from './streaming/useGroupStream';
 export { useRemoteStream } from './streaming/useRemoteStream';

app/soapbox/api/hooks/streaming/useHashtagStream.ts

@@ -0,0 +1,10 @@
+import { useTimelineStream } from './useTimelineStream';
+
+function useHashtagStream(tag: string) {
+  return useTimelineStream(
+    `hashtag:${tag}`,
+    `hashtag&tag=${tag}`,
+  );
+}
+
+export { useHashtagStream };