Replace CoInitialize calls with CoInitializeEx

Done to make single-threaded apartment (STA) usage more explicit.
CoInitializeEx(0, COINIT_APARTMENTTHREADED) does exactly the same as
CoInitialize(0), so there is no change in behavior.

REF: https://docs.microsoft.com/nb-no/windows/desktop/api/combaseapi/nf-combaseapi-coinitializeex



Change-Id: I2e2f77745b4360b1da1e6c284551d0f709aba546
Reviewed-by: Andre de la Rocha <andre.rocha@qt.io>
Reviewed-by: Oliver Wolff <oliver.wolff@qt.io>