feature make scroll-slider a CSS grid slider instead of flex

[GrimLink]

This upgrade will make it easier to create multi rowed sliders,
and drop the need to wait for flex gap.

Although Fylgja v2 will drop Safari 13 version need,
making this reason obsolete.

This update will need to check how it handles slide item auto sizing if no value is given.

Current solution can be the unit min-content.

Extra note: Drop the -webkit-overflow-scrolling from the styles, not needed since Safari 13