Android A11Y: Only access the main thread when it is not blocked

When the qtMainLoopThread calls QSGThreadedRenderLoop::polishAndSync(),
it waits for the QSGRenderThread.

In the QSGRenderThread, QAndroidPlatformOpenGLWindow::eglSurface()
calls QtAndroid::createSurface() and waits for the "android main
thread" to return a valid surface.
When the "android main thread" now calls "runInObjectContext" (e.g. by
calling QtAndroidAccessibility::childIdListForAccessibleObject()) it
waits for the qtMainLoopThread and the program is stuck in a deadlock.

To prevent this, we protect all BlockedQueuedConnection from the
"android main thread" to the qtMainLoopThread by acquiring the
AndroidDeadlockProtector.
When QAndroidPlatformOpenGLWindow::eglSurface() already acquired the
AndroidDeadlockProtector we abort the current A11y call with an emtpy
or default value.

Note: b8a95275440b8a143ee648466fd8b5401ee1e839 already tried to fix
this by checking "getSurfaceCount() != 0", but there are situations,
where a new surface is being created while an old surface is still
present.

Task-number: QTBUG-105958
Change-Id: Ie40e8654c99aace9e69b0b8412952fa22c89f071
Reviewed-by: Assam Boudjelthia <assam.boudjelthia@qt.io>
(cherry picked from commit b832a5ac72c6015b6509d60b75b2ce5d5e570800)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

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