test(email-templating): re-add email templating tests
As mentioned in !413 (b160ade4, comment 29156) I somehow left these files out of that MR. They include tests for the EmailTemplate (new) and HTMLTemplateService (existing).
As mentioned in !413 (b160ade4, comment 29156) I somehow left these files out of that MR. They include tests for the EmailTemplate (new) and HTMLTemplateService (existing).