Add ability to define table & tree cell hover style

[mgarin]

Currently hover is only tracked for component as a whole, but isn't tracked for separate cells of the table and tree components. There should be a support for hover style:

• For tree - in rowPainter, nodePainter and selectionPainter
• For table - in rowPainter, columnPainter, cellPainter and selectionPainter

Probably some other aspects of those components that rely on the hovered cell information may be optimized as well with the use of global hovered cell tracking implementation.