html: AttributeDict: __delitem__: add support for patch issuer

With the `issuer` argument it is possible to make changes that don't get rolled
out to the original issuer of the change. In this particular case this is meant
to be used for radio buttons to synchronize the `checked` property on the
backend with the frontend.

Signed-off-by: Florian Scherf <mail@florianscherf.de>

lona/html/attribute_dict.py

@@ -128,8 +128,22 @@ def __setitem__(self, name, value, issuer=None):
  issuer=issuer,
  )
 
- def __delitem__(self, name):
- self.pop(name, None)
+ def __delitem__(self, name, issuer=None):
+ with self._node.lock:
+ if name not in self._attributes:
+ return
+
+ del self._attributes[name]
+
+ self._node.document.add_patch(
+ node_id=self._node.id,
+ patch_type=self.PATCH_TYPE,
+ operation=OPERATION.REMOVE,
+ payload=[
+ name,
+ ],
+ issuer=issuer,
+ )
 
  def __eq__(self, other):
  with self._node.lock: