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_test.go

@@ -0,0 +1,20 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+//go:build maincoverage
+// +build maincoverage
+
+package main
+
+import (
+	"testing"
+)
+
+// TestRunMain can be used to track code coverage in integration tests.
+// To run this:
+// go test -coverpkg="<>" -ldflags '<>' -tags maincoverage -c ./cmd/mattermost/
+// ./mattermost.test -test.run="^TestRunMain$" -test.coverprofile=coverage.out
+// And then run your integration tests.
+func TestRunMain(t *testing.T) {
+	main()
+}