Includes mmctl into the mono-repo (#23091)

* Includes mmctl into the mono-repo

* Update to use the new public module paths

* Adds docs check to the mmctl CI

* Fix public utils import path

* Tidy up modules

* Fix linter

* Update CI tasks to use the new file structure

* Update CI references

server/cmd/mmctl/commands/utils_unix_test.go

@@ -0,0 +1,50 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package commands
+
+import (
+	"io/ioutil"
+	"net"
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestCheckValidSocket(t *testing.T) {
+	t.Run("should return error if the file is not a socket", func(t *testing.T) {
+		f, err := ioutil.TempFile(os.TempDir(), "mmctl_socket_")
+		require.NoError(t, err)
+		defer os.Remove(f.Name())
+		require.NoError(t, os.Chmod(f.Name(), 0600))
+
+		require.Error(t, checkValidSocket(f.Name()))
+	})
+
+	t.Run("should return error if the file has not the right permissions", func(t *testing.T) {
+		f, err := ioutil.TempFile(os.TempDir(), "mmctl_socket_")
+		require.NoError(t, err)
+		require.NoError(t, os.Remove(f.Name()))
+
+		s, err := net.Listen("unix", f.Name())
+		require.NoError(t, err)
+		defer s.Close()
+		require.NoError(t, os.Chmod(f.Name(), 0777))
+
+		require.Error(t, checkValidSocket(f.Name()))
+	})
+
+	t.Run("should return nil if the file is a socket and has the right permissions", func(t *testing.T) {
+		f, err := ioutil.TempFile(os.TempDir(), "mmctl_socket_")
+		require.NoError(t, err)
+		require.NoError(t, os.Remove(f.Name()))
+
+		s, err := net.Listen("unix", f.Name())
+		require.NoError(t, err)
+		defer s.Close()
+		require.NoError(t, os.Chmod(f.Name(), 0600))
+
+		require.NoError(t, checkValidSocket(f.Name()))
+	})
+}