MessagePort: implement disentanglement (#36654)

Implement
[disentangle](https://html.spec.whatwg.org/multipage/#disentangle)
Remove bespoke gc logic which now becomes unnecessary. 
Adds a wpt test that hits the "disentangle while in transfer" logic.
Updates streams code, fixing an error where disentanglement is
conditional on an error.

Test coverage: there are existing tests in
`/webmessaging/message-channels/close-event/explicitly-closed.tentative.window.js`
for the no transfer case, and the simple completed transfer case, and
this PR adds a test for the more complicated transfer in progress case.

Fix https://github.com/servo/servo/issues/36465

---------

Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com>

components/shared/constellation/structured_data/transferable.rs

@@ -77,7 +77,12 @@ impl MessagePortImpl {
         self.entangled_port
     }
 
-    /// Entanged this port with another.
+    /// <https://html.spec.whatwg.org/multipage/#disentangle>
+    pub fn disentangle(&mut self) -> Option<MessagePortId> {
+        self.entangled_port.take()
+    }
+
+    /// <https://html.spec.whatwg.org/multipage/#entangle>
     pub fn entangle(&mut self, other_id: MessagePortId) {
         self.entangled_port = Some(other_id);
     }