Android: New setup for AndroidDeviceManager

Also remove the now-unneeded plugin pimpl.

Change-Id: I37eaa91a2756e823d07323b54695e19860cb16ab
Reviewed-by: Jarek Kobus <jaroslaw.kobus@qt.io>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>

src/plugins/android/androiddevice.cpp

@@ -870,4 +870,9 @@ void setupAndroidDevice()
     static AndroidDeviceFactory theAndroidDeviceFactory;
 }
 
+void setupAndroidDeviceManager(QObject *guard)
+{
+    (void) new AndroidDeviceManager(guard);
+}
+
 } // Android::Internal