[HTML5]: JS modules can no longer be loaded from subdirectories

[XeduR]

Previously @Shchvova had added support for loading JS modules from subdirectories via https://github.com/coronalabs/submodule-platform-emscripten/commit/2c018f07a7661b2f95ab6ab34a3eed219b14de17, but this seems to be broken now.

If you run the js_plugin_test project from https://github.com/coronalabs/corona/tree/master/platform/emscripten/js_plugin_tests, it'll crash on browser as Solar2D fails to find the modules inside the scripts folder.

I've tested this Windows 10 running Solar2D 2022.3670.

[XeduR]

Adding a sample project that demonstrates this issue and the workaround.

jsPluginTest.zip