Add E2E for Toolkit

[Kocal]

I think these tests and modification on E2E app will be a bit special.

Ideally, I would like to have a dedicated page per Toolkit kits, with all components used (thanks to the examples/*.html.twig files)

[smnandre]

Ideally, I would like to have a dedicated page per Toolkit kits

I'm less and less sure we should have tests outside packages.

[Kocal]

The E2E tests can be found under src/**/assets, I'm not sure what you're talking about 😬

[smnandre]

"Ideally, I would like to have a dedicated page per Toolkit kits"