REORG: mux-quic: extract traces in a dedicated source file

REORG: mux-quic: extract traces in a dedicated source file

QUIC MUX implements several APIs to interface with stream, quic-conn and
app-ops layers. It is planified to better separate this roles, possibly
by using several files.

The first step is to extract QUIC MUX traces in a dedicated source
files. This will allow to reuse traces in multiple files.

The main objective is to be
able to support both TCP and HTTP proxy mode with a common base and add
specialized modules on top of it.

This should be backported up to 2.6.