[Check Deposit] Disallow creation unless feature enabled (#13634)

welp, they should only be able to deposit when we want them to
deposit...

Author: garyhtou

app/policies/check_deposit_policy.rb

@@ -10,7 +10,7 @@ def index?
   end
 
   def create?
-    OrganizerPosition.role_at_least?(user, record.event, :member) && !record.event.demo_mode?
+    OrganizerPosition.role_at_least?(user, record.event, :member) && !record.event.demo_mode? && check_deposits_enabled?
   end
 
   def view_image?