[Feature] Add Experience Gain Toggle. (#2676)

* [Feature] Add Experience Gain Toggle.

# Perl
- Add `$client->IsEXPEnabled()`.
- Add `$client->SetEXPEnabled(is_exp_enabled)`.

# Lua
- Add `client:IsEXPEnabled()`.
- Add `client:SetEXPEnabled(is_exp_enabled)`.

# Commands
- Add `#exptoggle [Toggle] - Toggle your or your target's experience gain.`.

# Notes
- Allows operators to turn on/off a player's experience gain individually without changing their rule values.
- The command allows operators to give players access to the command to disable their own experience gain.

zone/lua_client.h

@@ -455,6 +455,8 @@ public:
 	std::string GetGuildPublicNote();
 	void MaxSkills();
 	luabind::object GetAugmentIDsBySlotID(lua_State* L, int16 slot_id);
+	bool IsEXPEnabled();
+	void SetEXPEnabled(bool is_exp_enabled);
 
 	void ApplySpell(int spell_id);
 	void ApplySpell(int spell_id, int duration);