Intent to ship: CSS Module Scripts

[Daniel Minor]

As of Firefox 147, I intend to enable support for CSS Module Scripts by default on all platforms. It is currently available in Nightly builds, but disabled by default and controlled by the `layout.css.module-scripts.enabled` preference. CSS Module Scripts allow stylesheets to be imported using the JavaScript module system and import attributes, for more information, please see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules#loading_non-javascript_resources.

Chromium shipped support for this back in version 93 (https://developer.chrome.com/blog/new-in-chrome-93). Work does not appear to have started in Safari, the tracking bug is https://bugs.webkit.org/show_bug.cgi?id=227967.

Bug to turn on by default: https://bugzilla.mozilla.org/show_bug.cgi?id=1986681

Standard: https://html.spec.whatwg.org/#creating-a-css-module-script