[source-phase-imports] Support WASM script loading and compiling

As part of the Source Phase Import TC39 proposal, the HTML spec was
updated to allow the loading of module scripts with the application/wasm
MIME type. This CL:

Adds a WasmModuleScript subclass of ModuleScript to handle Wasm scripts,
this subclass has a reference to a v8::WasmModuleObject instead of a
reference to a v8::Module object.

Moves some logic handling v8::Module behind ModuleScript so that
WasmModuleScript can handle the special cases for v8::WasmModuleObject
through virtual function overrides.

Adds JavaScriptSourcePhaseImports blink flag.

Spec: https://html.spec.whatwg.org/multipage/webappapis.html

Bug: 42204365
Change-Id: I05c53efd2e169554c42a52df6c497b3747e07200
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6336964
Reviewed-by: Kouhei Ueno <kouhei@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Luis Pardo <lpardosixtos@microsoft.com>
Cr-Commit-Position: refs/heads/main@{#1454009}