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/config/migrations/postgres/000001_create_configurations.up.sql

@@ -0,0 +1,8 @@
+CREATE TABLE IF NOT EXISTS configurations (
+    id varchar(26),
+    value text NOT NULL,
+    createat bigint NOT NULL,
+    active boolean DEFAULT NULL,
+    PRIMARY KEY (id),
+    UNIQUE (active)
+);