Introduce Vite

[surma]

This PR introduces Vite as the build system for RGBDS Live.

I tried to do minimal changes to the code, so currently there’s still lots of globals and stuff, but the PR got big enough as it is. This already does some nice optimizations in that it bundles all the JavaScript and CSS files and minifies them, which should make the site load faster.

These are the changes introduced by this PR:

• Move website code to top-level so that the vite can put the bundled and optimized build into www.
• Make this a “proper” JS project by using package.json to import vite and to declare npm run build and npm run dev build scripts.
• add -s EXPORT_ES6=1 to Wasm builds so that the output is a ES6 module. This makes it easier to use the Wasm builds with vite.
• add -s ENVIRONMENT=web to rgbds builds so that the JS files don’t contain references to Node runtimes.
• type="module" which allows us to use ESM imports/exports in the code and will allow us to use top-level await in the future.
• Explicitly use globalThis to declare globals as ES6 modules have an isolated global scope by default.
• Remove script includes for Wasm builds and import their ES6 modules where they are used instead.

[surma]

Calling ./build.sh is still the right thing to do, exactly so that CI keeps working. Is it broken?

[avivace]

build.sh is not called at all atm in the CI, as all the final files would end up in the www folder anyway, so we need another step after the wasm builds to call build.sh

edit: I added it in https://github.com/gbdev/rgbds-live/pull/19/commits/d07f634cdc45b1cfd2c3125e1991863375ba36c7