Add constructions and Default for PduBuilder

simplify various RoomMemberEventContent constructions

Signed-off-by: Jason Volk <jason@zemos.net>

src/api/client/state.rs

@@ -177,10 +177,9 @@ async fn send_state_event_for_key_helper(
 			PduBuilder {
 				event_type: event_type.to_string().into(),
 				content: serde_json::from_str(json.json().get())?,
-				unsigned: None,
 				state_key: Some(state_key),
-				redacts: None,
 				timestamp,
+				..Default::default()
 			},
 			sender,
 			room_id,