[c2936] Implement more content related to Ulduar intro events

* proper handle Leviathan gauntlet event gossip
* allow DB scripts to handle the yells and movement of the intro event
* initialize hard mode towers and save the state of each of them

(based on commit SD2-WotLK [2933] - 7e08d59)

Signed-off-by: Xfurry <xfurry@scriptdev2.com>