This introduces an own QPA plugin for KWin. QtWayland's plugin is not
a good solution for KWin as QtWayland is meant for Wayland clients and
not for a Wayland server. Given that it makes more sense to have a very
minimal QPA plugin which supports the use cases we actually have.
With our own QPA plugin we should be able to improve the following
areas:
* no need to create Wayland server before QApplication
* Qt::BypassWindowManagerHint can be supported
* no workaround for creating OpenGL context in main thread
* sharing OpenGL context with Qt
* OpenGL context for Qt on libhybris backend
The plugin supports so far the following features:
* creating a QPlatformWindow using KWayland::Client (ShellSurface)
* creating a QPlatformBackingStore using a ShmPool
* creating a QPlatformOpenGLContext with Wayland::EGL
* or creating a QPlatformOpenGLContext which shares with KWin's scene
* creating a QPlatformScreen for each KWayland::Client::Output
* QPlatformNativeInterface compatible to QtWayland
Overwrite the platform name through the environment variable and ensure
that the plugin is not picked in non-kwin Wayland sessions as that puts
kglobalaccel5 into a crash restart loop.
BUG: 349911
The KGlobalAccelD which gets created by KWin needs a plugin for the
platform specific parts. This change introduces such a plugin. It's
linked against kwin so that it can integrate with the core.
On enable the plugin registers itself in the InputRedirection and
GlobalShortcutsManager checks the plugin whether a shortcut got
triggered.
As the loading of the plugin must happen after InputRedirection is
fully created a dedicated init method is added to InputRedirection.
REVIEW: 124187
