After #23370 fixed, we can implement dynamic-import of module script.

Spec: https://html.spec.whatwg.org/multipage/#fetch-an-import()-module-script-graph
Gecko code for registering dynamic-import hook: https://searchfox.org/mozilla-central/rev/501eb4718d73870892d28f31a99b46f4783efaa0/dom/script/ScriptLoader.cpp#960-1053