Create a constellation_traits crate (#36088)

This change creates a `constellation_traits` crate. Previously messages
to the `Constellation` were in the `compositing_traits` crate, which
came about organically. This change moves these to a new crate which
also contains data types that are used in both compositing/libservo and
script (ie types that cross the process boundary). The idea is similar
to `embedding_traits`, but this is meant for types not exposed to the
API.

This change allows deduplicating `UntrustedNodeAddress`, which
previously had two versions to avoid circular dependencies.

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

components/script/dom/documentorshadowroot.rs

@@ -4,9 +4,9 @@
 
 use std::fmt;
 
+use constellation_traits::UntrustedNodeAddress;
 use euclid::default::Point2D;
 use script_layout_interface::{NodesFromPointQueryType, QueryMsg};
-use script_traits::UntrustedNodeAddress;
 use servo_arc::Arc;
 use style::invalidation::media_queries::{MediaListKey, ToMediaListKey};
 use style::media_queries::MediaList;