Add iOS platform (refactor Mac into shared Apple platform impl)

Source/Tools/Flax.Build/Build/DepsModule.cs

@@ -34,6 +34,7 @@ namespace Flax.Build
             case TargetPlatform.Android:
             case TargetPlatform.Switch:
             case TargetPlatform.Mac:
+            case TargetPlatform.iOS:
                 options.OutputFiles.Add(Path.Combine(path, string.Format("lib{0}.a", name)));
                 break;
             default: throw new InvalidPlatformException(options.Platform.Target);