[Stimulus] Fasten lazy loading + add debug lazy:loading and lazy:loaded

[smnandre]

Q	A
Bug fix?	no
New feature?	yes
Issues	Fix #...
License	MIT

This PR..

1. improves the controller lazy loading by tuning algorithm (early exit, remove await, ...)

2. introduces two new debug events in the console to ease DX with lazy controllers

   • my-controller#lazy:loading when the lazy controller is detected in the DOM
   • my-controller#lazy:loaded after the file has been downloaded and imported

I would really like some feedback / tests IRL (especially with Webpack i'm not used to)

[github-actions]

📊 Packages dist files size difference

Thanks for the PR! Here is the difference in size of the packages dist files between the base branch and the PR.
Please review the changes and make sure they are expected.

File	Before (Size / Gzip)	After (Size / Gzip)
StimulusBundle
loader.js	3.2 kB / 910 B	3.8 kB+19% 📈 / 1.01 kB+14% 📈

[Kocal]

I would really like some feedback / tests IRL (especially with Webpack i'm not used to)

I will try to find some time to rebuild a Symfony + Encore app, but by reading your changes it looks fine to me (feel free to reping me if necessary)

[smnandre]

@MatTheCat ? 👼

[Kocal]

I'm testing

[Kocal]

Well... I've just realized, but to use Stimulus in a Symfony App with Webpack Encore, we use the https://github.com/symfony/stimulus-bridge ... which is not in this repository (and so not modified by this PR) 😅

[smnandre]

Well.... let me tell you i have no intention of coding in the Bridge hahaha

(i'll have a look but the lazy loading is done differently if i remember correctly)

[MatTheCat]

I’ve got nothing to test then? 🤔