Add config and UPO for HTML emails by default

Allowing HTML email only enables the User Preference Option.
$wgAllowHTMLEmail = true;
And, we set the UPO over-riding the default of 'plain-text'
$wgDefaultUserOptions['echo-email-format'] = 'html';

Author: freephile

src/roles/mediawiki/templates/LocalSettings.php.j2

@@ -313,9 +313,10 @@ $wgEmailAuthentication = $wgEnableEmail;
 $wgPasswordSender = '{{ wgPasswordSender }}';
 $wgEmergencyContact = '{{ wgEmergencyContact | default(wgPasswordSender) }}';
 
-
-
-
+// Allowing HTML email only enables the User Preference Option.
+// Without this set to true, users cannot choose to receive HTML email.
+$wgAllowHTMLEmail = true;
+$wgDefaultUserOptions['echo-email-format'] = 'html'; // default = plain-text