MINOR: mux-quic: close connection when reaching max-total streams

MINOR: mux-quic: close connection when reaching max-total streams

This commit completes the previous one which implements a new setting to
limit the number of streams usable by a client on a QUIC connection.

When the connection becomes idle after reaching this limit, it is
immediately closed. This is implemented by extending checks in
qcc_is_dead(). This results in a CONNECTION_CLOSE emission, which is
useful to free resources as soon as possible.