[RFC] Also animate the Cancel button
Adds a new class ProgressButton which is a ToolButton that displays the
screenshot delay. This is achieved by first painting the button, then
a smaller transparent button on top. The width of this overlay is proportional
to the elapsed time and the color is provided by KColorScheme::PositiveText.
Finally the icon and text are drawn on top.
Subscribers: ngraham, ndavis, Spectacle
Differential Revision: https://phabricator.kde.org/D22324