[FIX] mail: tests helpers: export mail setup registries

This commit exports the function responsible for setting up the mail registries in tests.

This is usefull if one doesn't want to instanciate a full webClient in tests and still have mail features.

Part-of: odoo/odoo#115799

addons/mail/static/tests/helpers/webclient_setup.js

@@ -156,7 +156,7 @@ export const setupManager = {
  * @returns {LegacyRegistry} The registry containing all the legacy services that will be passed
  * to the webClient as a legacy parameter.
  */
-async function setupMessagingServiceRegistries({
+export async function setupMessagingServiceRegistries({
     loadingBaseDelayDuration = 0,
     messagingBus,
     services,