Import application JS as a module

[afcapel]

The default javascript_include_tag added to application.html.erbhas type='text/javascript', which can cause problems when the bundler output is in ESM format. If the bundler outputs ESM code, we need to import it with type="module". Otherwise the module varibles end up in the global scope. See https://github.com/hotwired/turbo/pull/1077

This is especially problematic for bun.js, because bun can only emit ESM code at the moment.

This PR updates the install generator to add the type="module" attribute to the default javascript_include_tag.

defer is no longer needed, as JS modules are deferred by default.

Ref. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules#other_differences_between_modules_and_standard_scripts

This PR also updates the default config to ensure that all bundlers output ESM bundles.

• bun only supports ESM https://bun.sh/docs/bundler#format
• esbuild is configured to output ESM with the --format=esm flag https://esbuild.github.io/api/#format-esm
• webpacker is configured to output ESM bundles with output.chunkFormat https://webpack.js.org/configuration/output/#outputchunkformat
• rollup is configured to output ESM bundles with output.format https://rollupjs.org/configuration-options/#output-format

[psantos10]

I can confirm, adding type="module" fixes the problem:

<%= javascript_include_tag "application", "data-turbo-track": "reload", type: "module" %>