appDisplay: Show a dot when application is running

Show a dot in running applications.
Design request.
Why do we need this to have focus on folders?
theme: Match list row hover transition type of gtk

Currently we animate in both sides, hover on and hover off, and with
200ms. The downside of that it that it feels sluggish when passing with
the mouse hovering few items because the on transition is slow.

Match what gtk did for fix this for list rows hover state at
commit 52e91f1f74ecb943d, animating only on off hover. However,
gnome-shell doesn't support different kind of transitions for its css,
that will be lovely to have a easeOutQuad as well here.
panelMenu: Use a normal St.Bin to allow styling

Currently we don't add some style to ButtonBox like padding etc, we add
it programatically taking into account minimum padding and natural
padding. The thing is that with natural padding it works as expected
even for low resolutions.

As a design request, we need to style from css, and since the current
ButtonBox class doesn't add any worth functionality, change that and use
a simple St.Bin that allow normal styling.