[Quest API] Add GetLanguageName() to Perl/Lua. (#1860)

- Add quest::getlanguagename(language_id) to Perl.
- Add eq.get_language_name(language_id) to Lua.

zone/questmgr.h

@@ -115,6 +115,7 @@ public:
 	std::string getracename(uint16 race_id);
 	std::string getspellname(uint32 spell_id);
 	std::string getskillname(int skill_id);
+	std::string getlanguagename(int language_id);
 	void safemove();
 	void rain(int weather);
 	void snow(int weather);