Basically, this was done by:
1. Adding new class type in [common/djangoapps/student/message_types.py]
2. Adding new files for the ace template in a new directory named
[common/templates/student/edx_ace/emailchangeconfirmation]
3. Removing old template files
[confirm_email_change.txt] and [email_change_subject.txt]
from the directories:
[lms/templates/emails] and
[common/test/test_sites/test_site/templates/emails]
4. Converting the [confirm_email_change] code to use [ace.send()]
2. Add site configuration overrides to theming/helpers.py
3. Move microsite.get_value from theming/helpers to site_configuration/helpers
4. Move microsite_configuration.microsite.get_value usages to site_configuration.helpers.values
