class SetOutputBufferPartialSettings

This is the replacement for SetOutputBufferSettings().

When the client is using sysmem to allocate buffers, this message is

used instead of SetOutputBufferSettings()+AddOutputBuffer(). Instead, a

single SetOutputBufferPartialSettings() provides the StreamProcessor

with the client-specified output settings and a BufferCollectionToken

which the StreamProcessor will use to convey constraints to sysmem.

Both the client and the StreamProcessor will be informed of the

allocated buffers directly by sysmem via their BufferCollection channel

(not via the StreamProcessor channel).

Configuring output buffers is _required_ after OnOutputConstraints() is

received by the client with buffer_constraints_action_required true and

stream_lifetime_ordinal equal to the client's current

stream_lifetime_ordinal (even if there is an active stream), and is

_permitted_ any time there is no current stream.

Closing the current stream occurs on the StreamControl ordering domain,

so after a CloseCurrentStream() or FlushEndOfStreamAndCloseStream(), a

subsequent Sync() completion must be received by the client before the

client knows that there's no longer a current stream.

See also CompleteOutputBufferPartialSettings().