Move the document trait into a separate crate (#3035)

* add a default head method through eval
* remove the old document trait
* implement document for each platform
* pull out document into a dedicated crate to cut down on shared dependencies
---------

Co-authored-by: Jonathan Kelley <jkelleyrtp@gmail.com>

packages/desktop/headless_tests/utils.rs

@@ -50,7 +50,7 @@ pub fn mock_event_with_extra(id: &'static str, value: &'static str, extra: &'sta
                 "#
             );
 
-            eval(&js).await.unwrap();
+            document::eval(&js).await.unwrap();
         });
     })
 }