Switch connection handling to new_connection()

[ckreibich]

Establishing the connection state early has the benefit that code grabbing/logging the connection info sees the ID prior to the connection's state expiration.

@JustinAzoff, fyi!

[JustinAzoff]

yep.. and if you want a good test to ensure that this works. run it with https://github.com/corelight/zeek-long-connections and see if you get the community id stuff in the conn_long log.