Move the console log handling code to ui/console.[ch].

Change-Id: I8e554a8e17399d78b0ef29dfb68109a219cd9f1b
Reviewed-on: https://code.wireshark.org/review/4294
Petri-Dish: Gerald Combs <gerald@wireshark.org>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Gerald Combs <gerald@wireshark.org>