Add `FindInstance()` method for `MutatorAPI`

sources/KFRealm/Server/Unreal/MutatorAPI/KF1_MutatorAPI.uc

@@ -55,6 +55,26 @@ public function Mutator_OnModifyLogin_Slot OnModifyLogin(
     return Mutator_OnModifyLogin_Slot(signal.NewSlot(receiver));
 }
 
+public function Mutator FindInstance(class<Mutator> mutatorClass)
+{
+    local GameInfo  gameInfo;
+    local Mutator   result;
+
+    gameInfo = _server.unreal.GetGameType();
+    if (gameInfo == none) {
+        return none;
+    }
+    result = gameInfo.baseMutator;
+    while (result != none)
+    {
+        if (result.class == mutatorClass) {
+            return result;
+        }
+        result = result.nextMutator;
+    }
+    return none;
+}
+
 defaultproperties
 {
 }

sources/ServerRealm/API/Unreal/MutatorsAPI/MutatorAPI.uc

@@ -91,6 +91,18 @@ public function Mutator_OnMutate_Slot OnMutate(AcediaObject receiver);
 /* SIGNAL */
 public function Mutator_OnModifyLogin_Slot OnModifyLogin(AcediaObject receiver);
 
+/**
+ *  Method for finding a `Mutator` instance of a given class.
+ *  Note only once instance of `Mutator` class is supposed to be created.
+ *
+ *  @param  mutatorClass    Class of the `Mutator`, which instance method should
+ *      find.
+ *  @return Instance of `Mutator` of the given class. Guaranteed to be of class
+ *      `mutatorClass`. `none` iff there is no such instance added into
+ *      the game.
+ */
+public function Mutator FindInstance(class<Mutator> mutatorClass);
+
 defaultproperties
 {
 }