Move ScriptToConstellationMsg to constellation_traits (#36364)

This is the last big change necessary to create the
`constellation_traits` crate. This moves the data structure for messages
that originate from the `ScriptThread` and are sent to the
`Contellation` to `constellation_traits`, effectively splitting
`script_traits` in half. Before, `script_traits` was responsible for
exposing the API of both the `ScriptThread` and the `Constellation` to
the rest of Servo.

- Data structures that are used by `ScriptToConstellationMsg` are moved
  to `constellation_traits`. The dependency graph looks a bit like this:
  `script_layout_interface` depends on `script_traits` depends on
  `constellation_traits` depends on `embedder_traits`.
- Data structures that are used in the embedding layer
  (`UntrustedNodeAddress`, `CompositorHitTestResult`, `TouchEventResult`
  and `AnimationState`) are moved to embedder_traits, to avoid a
  dependency cycle between `webrender_traits` and
  `constellation_traits`.
- Types dealing with MessagePorts and serialization are moved to
  `constellation_traits::message_port`.

Testing: This is covered by existing tests as it just moves types
around.
Signed-off-by: Martin Robinson <mrobinson@igalia.com>

Signed-off-by: Martin Robinson <mrobinson@igalia.com>

components/script/dom/serviceworkerglobalscope.rs

@@ -8,6 +8,9 @@ use std::thread::{self, JoinHandle};
 use std::time::{Duration, Instant};
 
 use base::id::PipelineId;
+use constellation_traits::{
+    ScopeThings, ServiceWorkerMsg, WorkerGlobalScopeInit, WorkerScriptLoadOrigin,
+};
 use crossbeam_channel::{Receiver, Sender, after, unbounded};
 use devtools_traits::DevtoolScriptControlMsg;
 use dom_struct::dom_struct;
@@ -19,7 +22,6 @@ use net_traits::request::{
     CredentialsMode, Destination, InsecureRequestsPolicy, ParserMetadata, Referrer, RequestBuilder,
 };
 use net_traits::{CustomResponseMediator, IpcSend};
-use script_traits::{ScopeThings, ServiceWorkerMsg, WorkerGlobalScopeInit, WorkerScriptLoadOrigin};
 use servo_config::pref;
 use servo_rand::random;
 use servo_url::ServoUrl;