[Feature] Implemented /shield ability and related affects (#1494)

* shield ability initial work

* updates

* update

* updates

* Update client_process.cpp

* major updates

optimized
pet support
perl support

* updates

* minor update

* fix merge error

* requested changes

* variable fix

* optimization

* minor update

* Revert "optimization"

This reverts commit 27e11e758b.

* fix

reset variables on shield_target if shielder dies or zones during shielding.

* edge case fix

Catch and fix situations where shield target doesn't have shielder variable cleared. Can occur if shielder . uses ability when target is not in combat then zones.

* combined packet and mob function

Shield now uses a common pathway through ShieldAbility, added parameters to perl function

* Addressing formatting for Kayen

* Fix function typo

Co-authored-by: Akkadius <akkadius1@gmail.com>

zone/mob_ai.cpp

@@ -1128,6 +1128,10 @@ void Mob::AI_Process() {
 		if (focus_proc_limit_timer.Check())
 			FocusProcLimitProcess();
 
+		if (shield_timer.Check()) {
+			ShieldAbilityFinish();
+		}
+
 		auto npcSpawnPoint = CastToNPC()->GetSpawnPoint();
 		if (GetSpecialAbility(TETHER)) {
 			float tether_range = static_cast<float>(GetSpecialAbilityParam(TETHER, 0));