[PATCH 1/4] amstream/tests: Test that streams call IMediaStreamFilter::EndOfStream.

[Zebediah Figura (she/her)]

It's probably not the first time, but I feel like this is reaching a 
little too deep into the inner workings. Yes, it's documented, but 
unlike e.g. custom IAMMediaStream or IFilterGraph implementations, 
applications aren't really expected to plug in their own filters. Better 
to test it indirectly, especially when the behaviour isn't surprising.