Update Syphon Publishing

[vade]

Right now we support only BGRA / Unsigned int 8888 format frames, which forces Mercury to do pixel format conversion for us.

We need to hint that we support a variety of formats, or perhaps just a few.

Use bindToDrawFrameOfSize: and unbindAndPublish: to handle drawing, and integrate using CLIENT STORAGE and SHARED STORAGE and support RGBA, BGRA, YUV, 2vuy and whatever other BS formats we can to mitigate and pixel format conversion overhead.

[vade]

We use the GL optimizations but don't handle the pixel format situation.

[vade]

Since we are migrating to Metal, this may be moot, or at least, different?