Core/Common: Remove the no longer finite(x) macro for MSVC

Use std::isinfinite(f) instead.
Scripts/ICC: Summon Sealed Chest quest npc's upon the Lich King's Death

TODO: template updates for these npcs and gossips

Closes #10554
Closes #12591 (PR)

Signed-off-by: DDuarte <dnpd.dd@gmail.com>
DB/NPCs: Add missing gossip for Strahad Farsan

Closes #12613