DB/Creatures: set immunities for some Raidbosses

Closes #4947
Closes #9674
Closes #9675
DB/Creatures: update creature_text for Forgemaster Garfrost and add visual aura

Closes #9720
Core/DB - Reorganizing SQL's and Folders.
Merge branch 'master' of git://github.com/TrinityCore/TrinityCore