Build: Enable -Wimplicit-fallthrough on clang (#25056)

* Misc: Use [[fallthrough]] attribute instead of comment to mark intentional fallthroughs

Related: #25006

* Misc: Add some missing breaks (no-ops) to satisfy clang

Related: #25006
Closes #25055

* Build: Enable -Wimplicit-fallthrough on clang

Closes #25006

src/server/scripts/Battlefield/BattlefieldWG.cpp

@@ -773,6 +773,7 @@ void BattlefieldWG::DoCompleteOrIncrementAchievement(uint32 achievement, Player*
         case ACHIEVEMENTS_WIN_WG_100:
         {
             // player->UpdateCriteria();
+            break;
         }
         default:
         {

src/server/scripts/EasternKingdoms/BlackrockMountain/BlackrockSpire/instance_blackrock_spire.cpp

@@ -303,6 +303,7 @@ public:
                     for (GuidList::const_iterator itr = _incarceratorList.begin(); itr != _incarceratorList.end(); ++itr)
                         if (Creature* creature = instance->GetCreature(*itr))
                             creature->Respawn();
+                    break;
                 default:
                     break;
             }

src/server/scripts/EasternKingdoms/MagistersTerrace/instance_magisters_terrace.cpp

@@ -126,6 +126,7 @@ class instance_magisters_terrace : public InstanceMapScript
                     case NPC_SUNBLADE_BLOOD_KNIGHT:
                         if (creature->GetDistance(KaelthasTrashGroupDistanceComparisonPos) < 10.0f)
                             _kaelthasPreTrashGUIDs.insert(creature->GetGUID());
+                        break;
                     default:
                         break;
                 }

src/server/scripts/EasternKingdoms/ScarletMonastery/boss_high_inquisitor_fairbanks.cpp

@@ -146,6 +146,7 @@ struct boss_high_inquisitor_fairbanks : public BossAI
                 if (Unit* target = SelectTarget(SelectTargetMethod::MaxThreat, 0, 30.f, true, false))
                     DoCast(target, SPELL_SLEEP);
                 events.Repeat(30s);
+                break;
             default:
                 break;
         }

src/server/scripts/Kalimdor/CavernsOfTime/CullingOfStratholme/npc_arthas.cpp

@@ -1485,6 +1485,7 @@ public:
                             chromie->AI()->Talk(RP5_LINE_CHROMIE0);
                             chromie->AddNpcFlag(NPCFlags(UNIT_NPC_FLAG_GOSSIP | UNIT_NPC_FLAG_QUESTGIVER));
                         }
+                        break;
                     default:
                         break;
                 }

src/server/scripts/Kalimdor/zone_bloodmyst_isle.cpp

@@ -330,8 +330,11 @@ public:
                     std::list<Creature*> creatureList;
                     GetCreatureListWithEntryInGrid(creatureList, me, NPC_BLOODMYST_TESLA_COIL, 500.0f);
                     if (!creatureList.empty())
+                    {
                         for (std::list<Creature*>::iterator itr = creatureList.begin(); itr != creatureList.end(); ++itr)
                             (*itr)->InterruptNonMeleeSpells(true, SPELL_BLOODMYST_TESLA);
+                    }
+                    break;
                 }
                 default:
                     break;

src/server/scripts/Northrend/IcecrownCitadel/boss_professor_putricide.cpp

@@ -691,6 +691,7 @@ class boss_professor_putricide : public CreatureScript
                                 default:
                                     break;
                             }
+                            break;
                         }
                         default:
                             break;

src/server/scripts/Northrend/IcecrownCitadel/boss_rotface.cpp

@@ -352,6 +352,7 @@ class npc_big_ooze : public CreatureScript
                         case EVENT_STICKY_OOZE:
                             DoCastVictim(SPELL_STICKY_OOZE);
                             events.ScheduleEvent(EVENT_STICKY_OOZE, 15s);
+                            break;
                         default:
                             break;
                     }

src/server/scripts/Northrend/Naxxramas/boss_kelthuzad.cpp

@@ -815,6 +815,7 @@ public:
                         me->SetImmuneToPC(true);
                         me->DespawnOrUnsummon(30 * IN_MILLISECONDS); // just in case anything interrupts the movement
                         me->GetMotionMaster()->MoveTargetedHome();
+                        break;
                     default:
                         break;
                 }

src/server/scripts/Northrend/Naxxramas/boss_thaddius.cpp

@@ -796,6 +796,7 @@ public:
                         if (GameObject* coil = myCoilGO())
                             coil->SetGoState(GO_STATE_READY);
                         me->DespawnOrUnsummon(0, Hours(24 * 7));
+                        break;
                     default:
                         break;
                 }

src/server/scripts/Northrend/Ulduar/Ulduar/boss_flame_leviathan.cpp

@@ -357,6 +357,7 @@ class boss_flame_leviathan : public CreatureScript
                     case DATA_ORBIT_ACHIEVEMENTS:
                         if (ActiveTowers) // Only on HardMode
                             return ActiveTowersCount;
+                        break;
                     default:
                         break;
                 }

src/server/scripts/Outland/BlackTemple/instance_black_temple.cpp

@@ -169,6 +169,7 @@ class instance_black_temple : public InstanceMapScript
                         break;
                     case DATA_AKAMA_ILLIDAN_INTRO:
                         AkamaIllidanIntro = data;
+                        break;
                     default:
                         break;
                 }