Refactor calendar event functions to enhance parameter aliasing and improve documentation clarity

api/CalendarEventGetTextures.lua

@@ -4,6 +4,9 @@
 ---@alias eventType
 ---| 1 Raid dungeon
 ---| 2 Five-player dungeon
+---| 3 PvP event
+---| 4 Meeting
+---| 5 Other event
 
 ---@param eventType eventType
 ---@param expansion number Expansion to which the instance belongs; localized names can be found in the constants EXPANSION_NAME0, EXPANSION_NAME1, etc. (number)