Add bulk operations for orders (#3548)

* Add bulk operations for orders

* UI tweaks

* Fix test failures

* Fix filter form

* Add tests

* Run isort

src/pretix/control/forms/orders.py

@@ -159,7 +159,7 @@ class ReactivateOrderForm(ForceQuotaConfirmationForm):
     pass
 
 
-class CancelForm(ForceQuotaConfirmationForm):
+class CancelForm(forms.Form):
     send_email = forms.BooleanField(
         required=False,
         label=_('Notify customer by email'),
@@ -188,6 +188,7 @@ class CancelForm(ForceQuotaConfirmationForm):
     )
 
     def __init__(self, *args, **kwargs):
+        self.instance = kwargs.pop("instance")
         super().__init__(*args, **kwargs)
         change_decimal_field(self.fields['cancellation_fee'], self.instance.event.currency)
         self.fields['cancellation_fee'].widget.attrs['placeholder'] = floatformat(
@@ -205,6 +206,20 @@ class CancelForm(ForceQuotaConfirmationForm):
         return val
 
 
+class DenyForm(forms.Form):
+    send_email = forms.BooleanField(
+        required=False,
+        label=_('Notify customer by email'),
+        initial=True
+    )
+    comment = forms.CharField(
+        label=_('Comment (will be sent to the user)'),
+        help_text=_('Will be included in the notification email when the respective placeholder is present in the '
+                    'configured email text.'),
+        required=False,
+    )
+
+
 class MarkPaidForm(ConfirmPaymentForm):
     send_email = forms.BooleanField(
         required=False,