Migrate flame_forge2d to monorepo (#852)

* Migrate flame_forge2d to monorepo

* Put in the temporary publish to none

* Update docs

* Add dart_code_metrics

* Add analysis options

* Fix analyze issues

* Fix formatting

* Add dart_code_metrics to flame_forge2d example

packages/flame_forge2d/example/lib/boundaries.dart

@@ -0,0 +1,42 @@
+import 'package:flame_forge2d/flame_forge2d.dart';
+import 'package:flame_forge2d/forge2d_game.dart';
+import 'package:forge2d/forge2d.dart';
+import 'package:flame/game.dart';
+import 'package:flame_forge2d/body_component.dart';
+
+List<Wall> createBoundaries(Forge2DGame game) {
+  final topLeft = Vector2.zero();
+  final bottomRight = game.screenToWorld(game.viewport.effectiveSize);
+  final topRight = Vector2(bottomRight.x, topLeft.y);
+  final bottomLeft = Vector2(topLeft.x, bottomRight.y);
+
+  return [
+    Wall(topLeft, topRight),
+    Wall(topRight, bottomRight),
+    Wall(bottomRight, bottomLeft),
+    Wall(bottomLeft, topLeft),
+  ];
+}
+
+class Wall extends BodyComponent {
+  final Vector2 start;
+  final Vector2 end;
+
+  Wall(this.start, this.end);
+
+  @override
+  Body createBody() {
+    final shape = EdgeShape()..set(start, end);
+
+    final fixtureDef = FixtureDef(shape)
+      ..restitution = 0.0
+      ..friction = 0.3;
+
+    final bodyDef = BodyDef()
+      ..userData = this // To be able to determine object in collision
+      ..position = Vector2.zero()
+      ..type = BodyType.static;
+
+    return world.createBody(bodyDef)..createFixture(fixtureDef);
+  }
+}