* fix: #7604 shortened CTA text and added custom text for some notifs
Specifically, new-reply and new-chat have different CTA text as they
do not go to the forum home like other email templates send users to.
* fix: minor optimization as suggested by @barisusakli
* feat: re-designed digest
Updated design, logic no longer shows "no topics", just doesn't
show the list at all, teaser re-retrieved for digest so that it
always grabs a teaser even if there is no reply, changed default
email background to a light grey.
* fix: minor padding issues in digest
* fix: banned template
* fix: invitation.tpl
* fix: removed unused notif_chat and notif_post email templates
* fix: notification template
* fix: registration_accepted template
* fix: reset tpl
* fix: test tpl
* fix: email verify tpl
* fix: reset notify tpl
* fix: welcome tpl
* fix: additional minor font fixes
* fix: removed unused email header image assets
* fix: internationalised 'your daily digest' string
* fix: broken url in digest 🤦
* feat: added RTL support for emailer
/cc @PostMidnight
* Use standard language codes. Fallback for plugins.
* Fix transifex config
* Tab vs space here for some reason
* Remove redundancies
* config.relative_path instead of allcaps
* added upgrade script for existing users' accounts
