... and remove unused start, stop method from subclass.
Current implementation does not require subclass specific behavior
for the handle_frame() method.
Although the target platform of D3D11 decoding API are both desktop and UWP app,
DXVA header is blocked by "WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP)"
which is meaning that that's only for desktop app.
To workaround this inconsistent annoyingness, we need to define WINAPI_PARTITION_DESKTOP
regardless of target WinAPI partition.
