MINOR: quic: Make qc_build_frms() build ack-eliciting frames from a list

MINOR: quic: Make qc_build_frms() build ack-eliciting frames from a list

We want to be able to build ack-eliciting frames to be embedded into QUIC packets
from a prebuilt list of ack-eliciting frames. This will be helpful for the mux
which would like to send STREAM frames asap after having builts its own prebuilt
list.
To do so, we only add a parameter as struct list to this function to handle
such a prebuilt list.