Update qmacstyle for macOS 11 Big Sur

As it happened before, with a new OS released qmacstyle has some controls/metrics off/broken. This task will be a collection of sub-tasks related to those areas, requiring fixing.

• vertical slider is glitching (see picture attached), both visually and interaction-wise (all themes affected). (fixed by Tor Arne)
  -push button - wrong colour when pressed (dark mode only, on the picture, button on the left is Qt, on the right -
  AppKit-only app, both in pressed state)-
  circular slider looks different on all themes (arguably a problem, the native looks way too simplistic, have to check why we have it so fancy looking)
  tab widget is glitchy, both in light and dark theme. More important though, it (the native segmented control) has several styles and none of them looks like what it was pre-Big Sur. The closest to what we have now (with selected tab having a nice blue color -looks like a bunch of separate buttons (the style is called 'separate' btw) - see nativetabw.png attached). Can be 'faked' with un-clipped buttons (we already use buttons because of special colors/states we need)
• Focus rects are not drawn accurately