Rework Shazzrah script, add spell script for "Gate of Shazzrah"(23138)

Tweak the timer for "Arcane Explosion" accordingly to logged retail timers.

Implement the "Gate of Shazzrah"(23138) spell to remove hackfix which also didn't work as intended.

Due to incompompatibilities with how the other "Gate of Shazzrah"(23139) spell works, teleporting is being handled by the dummy effect in the former spell. This is because the teleport effect present in the spell doesn't provide the desireable results(it teleports the target to the caster, and applies the spell visual to the the target instead of the caster - all of which is the exact opposite of the correct behaviour.
Of course.