Core/Players: moved zone and area updating from a standalone timer into Heartbeat handling

[Ovahlord]

Changes proposed:

• turns out that retail and classic update their zone data on a per-heartbeat basis as well so we move the zone and area id handling over there

Tests performed:

• tested ingame

Is is worth noting that because of this relocation of the updating, zones, areas and consequently phasing and spell_area may take a bit longer as the old zone update timer was ticking every second while the heartbeat only fires once every 5200ms or on certain movement actions.

[Shauren]

Actually pointless code tbh (the whole periodic update)

• area/zone is updated on every relocation (Unit::UpdatePosition)
• because areatrigger packet now contains entered/exited bit (unlike 335), resting is handled entirely in WorldSession::HandleAreaTriggerOpcode

[Takenbacon]

* area/zone is updated on every relocation (Unit::UpdatePosition)

It shouldn't be, the vmap calls to get the area/zone ID from a position isn't cheap

* because areatrigger packet now contains entered/exited bit (unlike 335), resting is handled entirely in WorldSession::HandleAreaTriggerOpcode

Never trust the client.