Code cleanup.

This is not needed anymore.
Hover highlights again as you hover over related annotation.
We attach link prompt dialogs inside an annotation.

This makes event handlers work immediately on dialogs in the same way
they work on annotations.
Revert "We attach link prompt dialogs inside an annotation."

This reverts commit 0539c6a60b6fec207c1af5b8210ba048a14d4818.

This does not really work because dialogs are then forced to be inside
annotations list and you cannot drag them out without them being
clipped.
We have to duplicate all UX event handlers on dialogs.

This time we are making sure related highlights are made hovering when
you hover over a dialog, in the same way as we make hovering over
annotations.
Give UX feedback about highlights linked to annotations.

We should probably not overload hovering effect for three things:
annotations hover, annotations selection, annotations highlighted when
hovering over a related highlight.