Investigate potential solution to pass in additional options for scroll behaviour.

[christophstrobl]

In its current implementation scrolling is exclusive by default. This means any given position that is not Position#isInitial() will not be included in the result no matter which direction the scroll happens.

Going forward we should provide a concept similar to what we have with Pageable & PageRequest for scrolling to cover the following needs:

• Express in-/exclusion of a given ScrollPosition in the result.
• Express scroll direction (forward, backward)

The inclusion case for keyset based scrolling can be handled by adding another or with the present keyset and an equals comparison.

Related to: #3070