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/mysql/000037_create_sharedchannelremotes.up.sql

@@ -0,0 +1,42 @@
+CREATE TABLE IF NOT EXISTS SharedChannelRemotes (
+  Id varchar(26) NOT NULL,
+  ChannelId varchar(26) NOT NULL,
+  CreatorId varchar(26) DEFAULT NULL,
+  CreateAt bigint(20) DEFAULT NULL,
+  UpdateAt bigint(20) DEFAULT NULL,
+  IsInviteAccepted tinyint(1) DEFAULT NULL,
+  IsInviteConfirmed tinyint(1) DEFAULT NULL,
+  RemoteId varchar(26) DEFAULT NULL,
+  PRIMARY KEY (Id, ChannelId),
+  UNIQUE KEY ChannelId (ChannelId, RemoteId)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
+
+SET @preparedStatement = (SELECT IF(
+    (
+        SELECT COUNT(*) FROM INFORMATION_SCHEMA.COLUMNS
+        WHERE table_name = 'SharedChannelRemotes'
+        AND table_schema = DATABASE()
+        AND column_name = 'LastPostUpdateAt'
+    ) > 0,
+    'SELECT 1',
+    'ALTER TABLE SharedChannelRemotes ADD LastPostUpdateAt bigint;'
+));
+
+PREPARE alterIfNotExists FROM @preparedStatement;
+EXECUTE alterIfNotExists;
+DEALLOCATE PREPARE alterIfNotExists;
+
+SET @preparedStatement = (SELECT IF(
+    (
+        SELECT COUNT(*) FROM INFORMATION_SCHEMA.COLUMNS
+        WHERE table_name = 'SharedChannelRemotes'
+        AND table_schema = DATABASE()
+        AND column_name = 'LastPostId'
+    ) > 0,
+    'SELECT 1',
+    'ALTER TABLE SharedChannelRemotes ADD LastPostId VARCHAR(26);'
+));
+
+PREPARE alterIfNotExists FROM @preparedStatement;
+EXECUTE alterIfNotExists;
+DEALLOCATE PREPARE alterIfNotExists;