[Feature] Add support for -1 extradmgskill to allow all skills to be scaled. (#3136)

* [Feature] Add support for -1 extradmgskill to allow all skills to be scaled.

- `$mob->GetSkillDmgAmt(skill_id)` now uses `int` instead of `uint16`.

- `statbonuses:GetSkillDamageAmount(skill_id)` now uses `-1` properly.
- `mob:GetSkillDmgAmt(skill_id)` now uses `int` instead of `uint16`.

- A `-1` value in `extradmgskill` denotes the ability to scale all skills at once.
- Consolidated `AddItemBonuses()`, `AdditiveWornBonuses()`, `CalcItemBonuses()`, and `CalcRecommendedLevelBonus()` to mob-based methods to avoid code duplication.
- Bots, NPCs, and Mercs can now use additive worn effects if the rule is enabled, as well as all other proper stat bonuses that only clients had before.
- No SQL update required to change `extradmgskill` and `extradmgamt` to `int` as they already are this type in the database, just had to adjust `item_data.h` and `shareddb.cpp`.

* Update mob.cpp

* Cleanup.

* Cleanup.

* Move #include <vector> to header.

* Add method for GetExtraDamageSkills

* fix additembonuses

* Update bonuses.cpp

* Update mob.cpp

* Out of bounds.

* Update bonuses.cpp

---------

Co-authored-by: Aeadoin <109764533+Aeadoin@users.noreply.github.com>

common/skills.h

@@ -1,5 +1,5 @@
 /*	EQEMu: Everquest Server Emulator
-	
+
 	Copyright (C) 2001-2016 EQEMu Development Team (http://eqemulator.net)
 
 	This program is free software; you can redistribute it and/or modify
@@ -24,6 +24,7 @@
 
 #include <string>
 #include <map>
+#include <vector>
 
 
 namespace EQ
@@ -170,6 +171,7 @@ namespace EQ
 		bool IsMeleeDmg(SkillType skill);
 
 		extern const std::map<SkillType, std::string>& GetSkillTypeMap();
+		extern const std::vector<SkillType>& GetExtraDamageSkills();
 
 		std::string GetSkillName(SkillType skill);
 	} /*skills*/
@@ -305,7 +307,7 @@ namespace EQ
 
 		uint32 operator[](int skill_id) const { return const_cast<SkillProfile*>(this)->GetSkill(skill_id); }
 	};
-	
+
 } /*EQEmu*/
 
 #endif /*COMMON_SKILLS_H*/