[FIX] web: rework draggable_hook scrolling

In Knowledge, the scrollParent for the `Y` axis of an embedded ungrouped Kanban
view is the article body, which contains the draggable `container` (which is
itself contained in the scrollParent for the `X` axis).

This commit introduce 2 fixes related to the `draggable_hook_builder`:
- In `draggable_hook_builder`, `updateRects` was modifying values of the
  `containerRect` from values of the `scrollParent`. Then, the `containerRect`
  was used in `handleEdgeScrolling` to compute a scroll value to apply on the
  `scrollParent`, and when updating the dragged element position, to compute the
  boundaries for the dragged element. This commit stores values for
  `scrollParent` in `scrollParentRect` alongside the modified `containerRect`.
  `scrollParentRect` will be used to compute the scroll value based only on the
  dimensions of the scrollParent, and the modified `containerRect` will be used
  to compute the boundaries.
- The `scrollParent` in the `X` axis can be different from the `scrollParent` in
  the `Y` axis. This commit stores both of them individually so that one is not
  neglected when higher in the DOM than the other.

Task-3291771

closes odoo/odoo#121089

Signed-off-by: Julien Mougenot (jum) <jum@odoo.com>