mediafoundation: Implement generic URI source

GstMFSourceReader was introduced for an internal of mfvideosrc element to to read data from video capture device.

We can extend the usage of GstMFSourceReader to read data from any URI (http, file or so) if it's supported by MediaFoundation. Moreover, GstMFSourceReader can be enhanced to be able to read data from UWP file object which would be a more generic approach than !1001

See also https://docs.microsoft.com/en-us/windows/win32/api/mfreadwrite/nn-mfreadwrite-imfsourcereader