[Interfaces] Avoid string duplication.
[Interfaces] Added Media event cat/type for #1333.
[Interfaces] Support AllowedFields in ANFieldData for #1333.
[Util] Introduced GetStdANFields() for #1333.
[AN] NotificationRulesWidget::GetCurrentCat() for #1333.
[Util] Build fix.
[AN] Code style fixes.
[AN] Support standard fields in MatchConfigDialog for #1333.
[AN] Support Media category/types for #1333.