14240 extensibility ability to create multiple custom domains for each workspace 2 (#14307)

Adds a public-domain core-module. 
Reorganize custom-domain files properly

packages/twenty-server/src/engine/core-modules/approved-access-domain/services/approved-access-domain.service.ts

@@ -169,6 +169,9 @@ export class ApprovedAccessDomainService {
       throw new ApprovedAccessDomainException(
         'Approved access domain already registered.',
         ApprovedAccessDomainExceptionCode.APPROVED_ACCESS_DOMAIN_ALREADY_REGISTERED,
+        {
+          userFriendlyMessage: t`Approved access domain already registered.`,
+        },
       );
     }