Fix support for SOGoSieveFolderEncoding defaults

Fixed the following bugs in the mail filter editor:

1. Sieve folder encoding not respecting the SOGoSieveFolderEncoding
system defaults;
2. Conditions are still displayed when rule affects all messages;
3. Missing custom mail labels to "flag with" action.

UI/PreferencesUI/UIxPreferences.m

@@ -1622,6 +1622,14 @@ static NSArray *reminderValues = nil;
            userCanChangePassword];
 }
 
+//
+// Used wox by template
+//
+- (NSString *) sieveFolderEncoding
+{
+  return [[SOGoSystemDefaults sharedSystemDefaults] sieveFolderEncoding];
+}
+
 // - (NSString *) localeCode
 // {
 //   // WARNING : NSLocaleCode is not defined in <Foundation/NSUserDefaults.h>