MEDIUM: quic: implement quic-initial rules

MEDIUM: quic: implement quic-initial rules

Implement a new set of rules labelled as quic-initial.

These rules as specific to QUIC. They are scheduled to be executed early
on Initial packet parsing, prior a new QUIC connection instantiation.
Contrary to tcp-request connection, this allows to reject traffic
earlier, most notably by avoiding unnecessary QUIC SSL handshake
processing.

A new module quic_rules is created. Its main function
quic_init_exec_rules() is called on Initial packet parsing in function
quic_rx_pkt_retrieve_conn().

For the moment, only "accept" and "dgram-drop" are valid actions. Both
are final. The latter drops silently the Initial packet instead of
allocating a new QUIC connection.