(moderation): tickets command and note ticket.

Add new `tickets` command for viewing moderation tickets.
Add `Note` ticket implementation, with command.
Add `offer_delete` context utility.
Add `guild_moderator` command ward.

bot/modules/moderation/tickets/Ticket.py

@@ -32,6 +32,7 @@ class TicketState(FieldEnum):
     EXPIRING = 'EXPIRING', "Active"
     EXPIRED = 'EXPIRED', "Expired"
     PARDONED = 'PARDONED', "Pardoned"
+    REVERTED = 'REVERTED', "Reverted"
 
 
 class Ticket:
@@ -200,6 +201,10 @@ class Ticket:
     def state(self):
         return TicketState(self.data.ticket_state)
 
+    @property
+    def type(self):
+        return TicketType(self.data.ticket_type)
+
     async def update(self, **kwargs):
         """
         Update ticket fields.