[9318] Update quest XP formula

Use dbc store as base for real xp rewarded and also display xp reward accordingly in related packets.
Note there are still some smaller things that may need smaller adjustments and tweaks, these are on the todo-list.

Signed-off-by: NoFantasy <nofantasy@nf.no>

src/game/DBCStructure.h

@@ -1161,6 +1161,13 @@ struct QuestSortEntry
                                                             // 17 name flags
 };
 
+struct QuestXPLevel
+{
+    uint32      questLevel;                                 // 0
+    uint32      xpIndex[9];                                 // 1-9
+    //unk                                                   // 10
+};
+
 struct RandomPropertiesPointsEntry
 {
     //uint32  Id;                                           // 0 hidden key