Mono repo -> Master (#22553)

Combines the following repositories into one:

https://github.com/mattermost/mattermost-server
https://github.com/mattermost/mattermost-webapp
https://github.com/mattermost/focalboard
https://github.com/mattermost/mattermost-plugin-playbooks

server/channels/db/migrations/postgres/000037_create_sharedchannelremotes.up.sql

@@ -0,0 +1,15 @@
+CREATE TABLE IF NOT EXISTS sharedchannelremotes (
+    id character varying(26) NOT NULL,
+    channelid character varying(26) NOT NULL,
+    creatorid character varying(26),
+    createat bigint,
+    updateat bigint,
+    isinviteaccepted boolean,
+    isinviteconfirmed boolean,
+    remoteid character varying(26),
+    PRIMARY KEY(id, channelid),
+    UNIQUE(channelid, remoteid)
+);
+
+ALTER TABLE sharedchannelremotes ADD COLUMN IF NOT EXISTS LastPostUpdateAt bigint;
+ALTER TABLE sharedchannelremotes ADD COLUMN IF NOT EXISTS LastPostId character varying(26);