Fixes CMake error

StatusNotifierButton: switch to dbusmenu-lxqt

- Now returns floating point QPointF, should we keep
it instead of rounding and do floating point calculations?

- QEyesPlugin: remove deprecated setMargin() call

Qt::AA_UseHighDpiPixmaps has no effect now

Fix error:
static assertion failed: Pointer Meta Types must either point to
fully-defined types or be declared with Q_DECLARE_OPAQUE_POINTER(T *)

Q_DECLARE_METATYPE(...) must be used on fully qualified types
To avoid including plugin.h inside panelpluginsmodel.h,
the declaretion is moved.

setNamedColor() is deprecated in Qt6

TODO: Still don't know why prefix does not work

- Remove includes to QDesktopWidget

NOTE: Fix compilation with Xlib.h

Xlib.h is tricky because at line 82 has:

`#define Bool int`

And QtCore/qjsonvalue.h at line 28 has:

```
enum Type {
   ...
   Bool = 0x1,
   ...
}
```

This is fixed temporarily by moving Xlib.h
include to last and undefine Bool macro

Long term we want to hide X11 related code and encapsulate in a backend.
This backend will not expose X11 headers.

Many X11 specific functions got moved away from KWindowSystem header.

Long term we will move everything to a backend.

Use QScreen instead

Reported by Clazy

Reported by Clazy

Teporary objects get destroyed after call ends.
State is not updated.

- Reported by Clazy
- Also fix formatting a bit

- Use Qt::CaseInsensitive instead
- Pass argument by reference
- Format braces

NOTE: QX11Info::getTimestamp() was replaced with XCB_CURRENT_TIME macro.

I don't know if this breaks functionality.
Getting real timestamp involves messing with Qt private APIs

- Forward declare classes
- More refactory could be done here

- Use Xcb::ScopedCPointer for POD types

In Qt6 it's an alias

TODO: is behavior equivalent? Conversion flags...