Allow to opt-out of `PositionGhostAbsolutely` for `IOS`

[oemer-aran]

Problem Statement

I am using an overflow-hidden sortable container, which works perfectly fine on all devices, except IOS. I digged a bit into the code and saw, that only for IOS SortableJs is using position: absolute. I don't know why this is the case and there are no comments. I would like to opt-out of this behaviour and use position: fixed instead, so my ghost card wont be clipped.

Here is the code part where PositionGhostAbsolutely is set: https://github.com/SortableJS/Sortable/blob/ddd059717333d07b5b1125b7e1dc89514734bcf0/src/Sortable.js#L145

Proposed solution:

new Sortable(container, { position: 'fixed' })

// or

new Sortable(container, { iosPosition: 'fixed' })