Add ActiveQt Media Player example

The Media Player example uses the Microsoft Media Player ActiveX
control to implement a functional media player application.
This example demonstrates how a Qt application can communicate with
embedded ActiveX controls using signals, slots and the dynamicCall()
function.

Task-number: QTBUG-60636
Change-Id: Ie2f65d3d8796076b2c18d5fa561b709035a53e79
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>