Basic support for Mosaico templates.

TODO:
- Allow choosing a mosaico template in a mosaico-based template
- Integrate the custom mosaico templates with templates (endpoint for retrieving a mosaico template, replacement of URL_BASE and PLACEHOLDER tags
- Implement support for MJML-based Mosaico templates
- Implement support for MJML-based templates
- Implement support for GrapeJS-based templates

routes/mosaico.js

@@ -123,6 +123,7 @@ router.getAsync('/img/:type/:fileId', passport.loggedIn, async (req, res) => {
     } else {
         width = sanitizeSize(width, 1, 2048, 600, false);
         height = sanitizeSize(height, 1, 2048, 300, true);
+        // TODO - validate that one has the rights to read this ???
         image = await resizedImage(req.query.src, method, width, height);
     }