feat(Core/Misc): change how Position struct is retrieved (#9017)

Update Position::GetPosition() and similar methods signatures to reflect 2a4c9bc changes by return a Position object instead of accepting a Position parameter by reference.

Cherry pick of https://github.com/TrinityCore/TrinityCore/commit/2585e799f95f259dd4b422daf15ef7963173c408

src/server/scripts/Outland/TempestKeep/Mechanar/boss_mechano_lord_capacitus.cpp

@@ -118,8 +118,7 @@ public:
                     break;
                 case EVENT_SUMMON_NETHER_CHARGE:
                     {
-                        Position pos;
-                        me->GetRandomNearPosition(pos, 8.0f);
+                        Position pos = me->GetRandomNearPosition(8.0f);
                         me->SummonCreature(NPC_NETHER_CHARGE, pos, TEMPSUMMON_TIMED_DESPAWN, 18000);
                         events.ScheduleEvent(EVENT_SUMMON_NETHER_CHARGE, 5000);
                         break;