move users service to app directory (#18257)

app/user.go

@@ -19,10 +19,10 @@ import (
 	"github.com/mattermost/mattermost-server/v6/app/email"
 	"github.com/mattermost/mattermost-server/v6/app/imaging"
 	"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/model"
 	"github.com/mattermost/mattermost-server/v6/plugin"
-	"github.com/mattermost/mattermost-server/v6/services/users"
 	"github.com/mattermost/mattermost-server/v6/shared/i18n"
 	"github.com/mattermost/mattermost-server/v6/shared/mfa"
 	"github.com/mattermost/mattermost-server/v6/shared/mlog"