Button & ToolButton: Match qqc2-desktop-style behavior
Match the dimensions roughly with qqc2-desktop-style buttons.
There is a special property in qqc2-desktop-style Buttons, where they have a minimum width if there is text in them. We implement this property here as well, since dialogs otherwise look kind of strange.
qqc2-breeze-style before:
qqc2-breeze-style after:
qqc2-desktop-style: