[10989] Implement post-3.1 and later fishing changes.

* Fishing now prowide junk loot at fail skill check.
  This can be disabled for old way work using SkillFail.Loot.Fishing option.
  Junk loot expected to be listed in fishing_loot_template entry 0.

* Fishing can gain skill grow at skill fail check case.
  Controlled by SkillFail.Gain.Fishing option.

* Fishing from fishing pool gameobject can't be fail.
  Controlled by SkillFail.Possible.FishingPool

src/game/LootMgr.cpp

@@ -1171,6 +1171,9 @@ void LoadLootTemplates_Fishing()
                 ids_set.erase(areaEntry->ID);
     }
 
+    // by default (look config options) fishing at fail provide junk loot, entry 0 use for store this loot
+    ids_set.erase(0);
+
     // output error for any still listed (not referenced from appropriate table) ids
     LootTemplates_Fishing.ReportUnusedIds(ids_set);
 }