[Gekidou] - Channel Intro (#5846)

* Channel Intro

* Move avatar margins to post component per feedback review

* Channel intro redesign

* Fix preferences unit test

* Change group intro sizes

* Add Bot tag to DM Intro if they have it

* fix channel isTablet layout on split screen

* update snapshot

types/api/channels.d.ts

@@ -41,6 +41,11 @@ type ChannelWithTeamData = Channel & {
     team_name: string;
     team_update_at: number;
 }
+type ChannelMember = {
+    id?: string;
+    channel_id: string;
+    user_id: string;
+}
 type ChannelMembership = {
     id?: string;
     channel_id: string;