feat: Added glow effect using maskFilter (#2129)

examples/lib/stories/effects/glow_effect_example.dart

@@ -0,0 +1,39 @@
+import 'package:flame/components.dart';
+import 'package:flame/effects.dart';
+import 'package:flame/game.dart';
+import 'package:flame/input.dart';
+import 'package:flutter/material.dart';
+
+void main() {
+  runApp(GameWidget(game: GlowEffectExample()));
+}
+
+class GlowEffectExample extends FlameGame with TapDetector {
+  static const String description = '''
+    In this example we show how the `GlowEffect` can be used.
+  ''';
+
+  @override
+  Future<void> onLoad() async {
+    final paint = Paint()
+      ..color = const Color(0xff39FF14)
+      ..style = PaintingStyle.stroke;
+
+    add(
+      CircleComponent(
+        radius: 50,
+        position: Vector2(300, 400),
+        paint: paint,
+      )..add(
+          GlowEffect(
+            10.0,
+            EffectController(
+              duration: 3,
+              reverseDuration: 1.5,
+              infinite: true,
+            ),
+          ),
+        ),
+    );
+  }
+}