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/cmd/mattermost/main.go

@@ -0,0 +1,23 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package main
+
+import (
+	"os"
+
+	"github.com/mattermost/mattermost-server/v6/server/cmd/mattermost/commands"
+	// Import and register app layer slash commands
+	_ "github.com/mattermost/mattermost-server/v6/server/channels/app/slashcommands"
+	// Plugins
+	_ "github.com/mattermost/mattermost-server/v6/model/oauthproviders/gitlab"
+
+	// Enterprise Imports
+	_ "github.com/mattermost/mattermost-server/v6/server/channels/imports"
+)
+
+func main() {
+	if err := commands.Run(os.Args[1:]); err != nil {
+		os.Exit(1)
+	}
+}