[VCM] Fix issues on certain systems (#12481)

- Don't depend on System.Windows.Forms in the Settings -> use callback instead
- Fix overlay image setting saving
- Use dynamic DLL loading in Interop
- Load VCM only when mf.dll is available

src/modules/videoconference/VideoConferenceShared/MediaFoundationAPIProvider.h

@@ -0,0 +1,14 @@
+#pragma once
+
+#include <mfapi.h>
+#include <mfidl.h>
+
+#include "DLLProviderHelpers.h"
+
+DECLARE_DLL_PROVIDER_BEGIN(mfplat)
+DECLARE_DLL_FUNCTION(MFCreateAttributes)
+DECLAR_DLL_PROVIDER_END
+
+DECLARE_DLL_PROVIDER_BEGIN(mf)
+DECLARE_DLL_FUNCTION(MFEnumDeviceSources)
+DECLAR_DLL_PROVIDER_END