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_module.js

@@ -0,0 +1,6 @@
+// No top-level import/export — auto-detection alone would classify this as a
+// classic script. `with_module(true)` on the asset overrides that and forces
+// the CLI to emit `<script type="module">` and run esbuild with the ESM
+// pipeline. The playwright spec asserts both that the global is set and that
+// the script tag actually has `type="module"`.
+window.__esm_module_value = "ok-module";