autodetect js module type - only bundle esm (#5515)

* wip: autodetect esm

* finish fixes

* thread minify through

* add sweetalert2

* Fix default bundle types

* ts-ignore

* small nits

* small more nits

* shrink flamegraph

packages/playwright-tests/cli-optimization/assets/esm_auto.js

@@ -0,0 +1,7 @@
+// No `with_module(true)` is set on the asset — the CLI must detect this file
+// as ESM from its source (top-level `export`) and emit `<script type="module">`
+// automatically. The `import.meta.url` reference would be a syntax error if the
+// script tag were a classic <script>.
+export const value = "ok-auto";
+window.__esm_auto_value = value;
+window.__esm_auto_meta = typeof import.meta.url;