MEDIUM: quic: handle out-of-order ACK at streamdesc layer

MEDIUM: quic: handle out-of-order ACK at streamdesc layer

qc_stream_desc_ack() is the entrypoint for streamdesc layer to handle a
new acknowledgement of previously emitted STREAM data.

Previously, it was only able to deal with in-order ACK offset. The
caller was responsible to buffer out-of-order ACKs. Change this by
dealing with the latter case directly in qc_stream_desc_ack(). This
notably simplify ACK handling in quic_rx module.