Add announcements (#12662)

* Add announcements

Fix #11006

* Add reactions to announcements

* Add admin UI for announcements

* Add unit tests

* Fix issues

- Add `with_dismissed` param to announcements API
- Fix end date not being formatted when time range is given
- Fix announcement delete causing reactions to send streaming updates
- Fix announcements container growing too wide and mascot too small
- Fix `all_day` being settable when no time range is given
- Change text "Update" to "Announcement"

* Fix scheduler unpublishing announcements before they are due

* Fix filter params not being passed to announcements filter

app/javascript/mastodon/actions/importer/normalizer.js

@@ -76,7 +76,6 @@ export function normalizeStatus(status, normalOldStatus) {
 
 export function normalizePoll(poll) {
   const normalPoll = { ...poll };
-
   const emojiMap = makeEmojiMap(normalPoll);
 
   normalPoll.options = poll.options.map((option, index) => ({
@@ -87,3 +86,12 @@ export function normalizePoll(poll) {
 
   return normalPoll;
 }
+
+export function normalizeAnnouncement(announcement) {
+  const normalAnnouncement = { ...announcement };
+  const emojiMap = makeEmojiMap(normalAnnouncement);
+
+  normalAnnouncement.contentHtml = emojify(normalAnnouncement.content, emojiMap);
+
+  return normalAnnouncement;
+}