qml: do not auto scroll text when hovered & scroll when there is visual focus

I have not observed any other desktop application that behaves as such on mouse interaction. If auto scrolling text is necessary for televisions and such, then visualFocus would be more appropriate to initiate text auto scrolling as I do here.

At the same time, custom Label recently gained the ability of showing tool tip when hovered. Currently, text auto scroller and the attached tool tip conflict with each other on hovered state.