script: Pass &mut JSContext to tasks (#41756)

This change is reviewable per commits:
In first commit we added `&mut JSContext` to `run_box` (it is very hard
to bring `&mut JSContext` to `remove_script_and_layout_blocker`).
In second commit we pass `&mut JSContext` to `run_once`.
In third commit we added support for accepting `&mut JSContext` in
closures of `task!` macro and lastly we demo new macro invocations (to
ensure they actually compile)

Testing: Just refactor, but should be covered by WPT
Part of #40600

---------

Signed-off-by: sagudev <16504129+sagudev@users.noreply.github.com>

components/script/script_thread.rs

@@ -2009,7 +2009,7 @@ impl ScriptThread {
                     let global = self.documents.borrow().find_global(id);
                     global.map(|global| enter_realm(&*global))
                 });
-                task.run_box()
+                task.run_box(cx)
             },
             MainThreadScriptMsg::Common(CommonScriptMsg::CollectReports(chan)) => {
                 self.collect_reports(chan)