move users service to app directory (#18257)

app/user_test.go

@@ -18,11 +18,11 @@ import (
 	"github.com/stretchr/testify/require"
 
 	"github.com/mattermost/mattermost-server/v6/app/request"
+	"github.com/mattermost/mattermost-server/v6/app/users"
 	"github.com/mattermost/mattermost-server/v6/einterfaces"
 	"github.com/mattermost/mattermost-server/v6/einterfaces/mocks"
 	"github.com/mattermost/mattermost-server/v6/model"
 	oauthgitlab "github.com/mattermost/mattermost-server/v6/model/gitlab"
-	"github.com/mattermost/mattermost-server/v6/services/users"
 	"github.com/mattermost/mattermost-server/v6/store"
 	storemocks "github.com/mattermost/mattermost-server/v6/store/storetest/mocks"
 	"github.com/mattermost/mattermost-server/v6/utils/testutils"