[Impeller] Add golden for clipped+transformed blur. (#48886)

This is a simple golden intended to smoketest potential issues when applying the coverage hint in the blur. Expected results:
![Screenshot 2023-12-11 at 12 03 50�PM](https://github.com/flutter/engine/assets/919017/251978b7-e6b4-4863-97f0-9a9a236f05ea)

Author: bdero

impeller/aiks/aiks_unittests.cc

@@ -4555,5 +4555,34 @@ TEST_P(AiksTest, GaussianBlurWithoutDecalSupport) {
   ASSERT_TRUE(OpenPlaygroundHere(canvas.EndRecordingAsPicture()));
 }
 
+// Smoketest to catch issues with the coverage hint.
+// Draws a rotated blurred image within a rectangle clip. The center of the clip
+// rectangle is the center of the rotated image. The entire area of the clip
+// rectangle should be filled with opaque colors output by the blur.
+TEST_P(AiksTest, GaussianBlurRotatedAndClipped) {
+  Canvas canvas;
+  std::shared_ptr<Texture> boston = CreateTextureForFixture("boston.jpg");
+  Rect bounds =
+      Rect::MakeXYWH(0, 0, boston->GetSize().width, boston->GetSize().height);
+  Vector2 image_center = Vector2(bounds.GetSize() / 2);
+  Paint paint = {.image_filter =
+                     ImageFilter::MakeBlur(Sigma(20.0), Sigma(20.0),
+                                           FilterContents::BlurStyle::kNormal,
+                                           Entity::TileMode::kDecal)};
+  Vector2 clip_size = {150, 75};
+  Vector2 center = Vector2(1024, 768) / 2;
+  canvas.Scale(GetContentScale());
+  canvas.ClipRect(
+      Rect::MakeLTRB(center.x, center.y, center.x, center.y).Expand(clip_size));
+  canvas.Translate({center.x, center.y, 0});
+  canvas.Scale({0.6, 0.6, 1});
+  canvas.Rotate(Degrees(25));
+
+  canvas.DrawImageRect(std::make_shared<Image>(boston), /*source=*/bounds,
+                       /*dest=*/bounds.Shift(-image_center), paint);
+
+  ASSERT_TRUE(OpenPlaygroundHere(canvas.EndRecordingAsPicture()));
+}
+
 }  // namespace testing
 }  // namespace impeller