quic: Refactor connections closing and deletion

quic: Refactor connections closing and deletion

This code should handle the 3 following cases:
- Active close
quic_proto_on_close sets state to ACTIVE_CLOSING
send packets eventually returns an error, calling
quic_connection_closed which deletes the connection

- Passive close
quic_on_closed_by_peer -> set state to PASSIVE_CLOSING
"race" between app confirmation (calling quic_proto_on_close) and
quicly signalling that it's done (triggers call to
quic_connection_closed).
If quic_connection_closed is called first, it sets the state to
PASSIVE CLOSING QUIC CLOSED, then when quic_proto_on_close is called
it frees the connection.
If quic_proto_on_close is called first, it sets the state to PASSIVE
CLOSING APP CLOSED, then when quic_connection_closed is called it frees
the connection

- Error close (reset)
quic_connection_closed is called in state READY. This means a timeout
or protocol error happened. This calls session_transport_reset_notify,
the app should confirm the deletion and quic_proto_on_close will be
called to delete the connection.

Change-Id: I3acbf9b079ed2439bdbb447197c428c78915d8c0
Signed-off-by: Aloys Augustin <aloaugus@cisco.com>
Type: feature