Add Guardian Angel protection checks

MiraAPI/Networking/CustomMurderRpc.cs

@@ -93,7 +93,12 @@ public static class CustomMurderRpc
             beforeMurderEvent.Cancel();
         }
 
-        if (beforeMurderEvent.IsCancelled)
+        if (target.ProtectedByGa())
+        {
+            beforeMurderEvent.Cancel();
+            murderResultFlags = MurderResultFlags.FailedProtected;
+        }
+        else if (beforeMurderEvent.IsCancelled)
         {
             murderResultFlags = MurderResultFlags.FailedError;
         }

MiraAPI/Utilities/Extensions.cs

@@ -156,6 +156,16 @@ public static class Extensions
         return TutorialManager.InstanceExists || AmongUsClient.Instance.HostId == playerControl.OwnerId;
     }
 
+    /// <summary>
+    /// Checks if a PlayerControl is protected by a Guardian Angel.
+    /// </summary>
+    /// <param name="playerControl">The player you're checking for.</param>
+    /// <returns>If the player is protected, true, else false.</returns>
+    public static bool ProtectedByGa(this PlayerControl playerControl)
+    {
+        return playerControl.protectedByGuardianId > -1;
+    }
+
     /// <summary>
     /// Used to convert a System.Collections.Generic.List to Il2cppSystem.
     /// </summary>