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/000022_create_sessions.up.sql

@@ -0,0 +1,37 @@
+CREATE TABLE IF NOT EXISTS sessions (
+    id VARCHAR(26) PRIMARY KEY,
+    token VARCHAR(26),
+    createat bigint,
+    expiresat bigint,
+    lastactivityat bigint,
+    userid VARCHAR(26),
+    deviceid VARCHAR(512),
+    roles VARCHAR(64),
+    isoauth boolean,
+    props VARCHAR(1000)
+);
+
+ALTER TABLE sessions ADD COLUMN IF NOT EXISTS expirednotify boolean;
+
+CREATE INDEX IF NOT EXISTS idx_sessions_user_id ON sessions (userid);
+CREATE INDEX IF NOT EXISTS idx_sessions_token ON sessions (token);
+CREATE INDEX IF NOT EXISTS idx_sessions_expires_at ON sessions (expiresat);
+CREATE INDEX IF NOT EXISTS idx_sessions_create_at ON sessions (createat);
+CREATE INDEX IF NOT EXISTS idx_sessions_last_activity_at ON sessions (lastactivityat);
+
+DO $$
+	<< migrate_if_version_below_5120 >>
+DECLARE
+	current_db_version VARCHAR(100) := '';
+BEGIN
+	SELECT
+		value INTO current_db_version
+	FROM
+		systems
+	WHERE
+		name = 'Version';
+	IF (string_to_array(current_db_version, '.') < string_to_array('5.12.0', '.')) THEN	
+        DELETE FROM sessions where expiresat > 3000000000000;
+	END IF;
+END migrate_if_version_below_5120
+$$;