MINOR: mux-quic: complete functions to detect stream type

Improve the functions used to detect the stream characteristics :
uni/bidirectional and local/remote initiated.

Most notably, these functions are now designed to work transparently for
a MUX in the frontend or backend side. For this, we use the connection
to determine the current MUX side. This will be useful if QUIC is
implemented on the server side.
2 files changed