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/Players: Fixed tabard championing in normal modes of WotLK level 80 dungeons

Closes #9227
Core/AuctionHouse: Fixed field type mismatches when saving auction to database (db fields are unsigned int) and prevent posting auctions with bids or buyouts over gold cap

Closes #9762
Core/Players: Fixed deleting characters unlinked from accounts

Closes #9764
Merge branch 'master' of https://github.com/TrinityCore/TrinityCore