feat: add chat handler methods

[r-o-b-o-t-o]

• Adds class ChatHandler
  • GetPlayer()
  • GetSelectedCreature()
  • GetSelectedObject()
  • GetSelectedPlayer()
  • GetSelectedPlayerOrSelf()
  • GetSelectedUnit()
  • HasLowerSecurity()
  • HasLowerSecurityAccount()
  • HasSentErrorMessage()
  • IsAvailable()
  • IsConsole()
  • SendGlobalGMSysMessage()
  • SendGlobalSysMessage()
  • SendSysMessage()
• Adds ChatHandler argument passed to PLAYER_EVENT_ON_COMMAND hook
  • The arguments are now (event, player, command, chatHandler)
  • Example usage:

local PLAYER_EVENT_ON_COMMAND = 42

RegisterPlayerEvent(PLAYER_EVENT_ON_COMMAND, function(event, player, text, chatHandler)
	if text ~= "testcmd" then
		return true
	end

	if not chatHandler:IsAvailable(3) then
		-- Restrict usage to sec level 3 and higher
		return true
	end

	chatHandler:SendSysMessage("Test command!") -- Gets printed to the chat if ran from a player, and printed to console otherwise
	return false
end)

This PR needs azerothcore/mod-eluna-lua-engine#89

[r-o-b-o-t-o]

Must be merged at the same time as azerothcore/mod-eluna-lua-engine#89

[55Honey]

Tested with 55Honey/Acore_SendAndBind#6 and 55Honey/Acore_ElunaTest#3
Works like a charm.