Rework carousel item

If you are ok with that I will create a change record.

grimreaper → credited pdureau → .

Automatically closed - issue fixed for 2 weeks with no activity.

@pdureau,

As discussed on phone, I am re-opening this issue because I think it broke Views usage.

I am ok to revert the change for 5.0.x as I think this would require new mechanism from UIP2.

For views: we need to be able to control the "active" boolean prop with the fact that the element is the first (or nth) result.
For field formatters: we need to be able to control the "active" boolean prop with the fact that the element is the first (or nth) element/delta.

Remove active prop.
Custom JS that will check all carousel items and will place the active class on the first one if none have the active class.

Automatically closed - issue fixed for 2 weeks with no activity.