feat: Add PIP (Picture-in-Picture) support (#2391)

- Closes: #1657

tests/components-lib/media-player/image.test.ts

@@ -114,4 +114,10 @@ describe('ImageMediaPlayerController', () => {
       expect(controller.getFullscreenElement()).toBeNull();
     });
   });
+
+  it('should return null for getPIPElement', () => {
+    const controller = new ImageMediaPlayerController(createLitElement(), () => null);
+
+    expect(controller.getPIPElement()).toBeNull();
+  });
 });

tests/components-lib/media-player/jsmpeg.test.ts

@@ -249,4 +249,14 @@ describe('JSMPEGMediaPlayerController', () => {
       expect(controller.getFullscreenElement()).toBeNull();
     });
   });
+
+  it('should return null for getPIPElement', () => {
+    const controller = new JSMPEGMediaPlayerController(
+      createLitElement(),
+      () => mock<JSMpeg.VideoElement>(),
+      () => null,
+    );
+
+    expect(controller.getPIPElement()).toBeNull();
+  });
 });

tests/components-lib/media-player/updating-image.test.ts

@@ -189,4 +189,14 @@ describe('UpdatingImageMediaPlayerController', () => {
       expect(controller.getFullscreenElement()).toBeNull();
     });
   });
+
+  it('should return null for getPIPElement', () => {
+    const controller = new UpdatingImageMediaPlayerController(
+      createLitElement(),
+      () => null,
+      () => mock<CachedValueController<string>>(),
+    );
+
+    expect(controller.getPIPElement()).toBeNull();
+  });
 });

tests/components-lib/media-player/video.test.ts

@@ -270,4 +270,20 @@ describe('VideoMediaPlayerController', () => {
       expect(controller.getFullscreenElement()).toBeNull();
     });
   });
+
+  describe('should get PIP element', () => {
+    it('should return video element when available', () => {
+      const video = mock<HTMLVideoElement>();
+
+      const controller = new VideoMediaPlayerController(createLitElement(), () => video);
+
+      expect(controller.getPIPElement()).toBe(video);
+    });
+
+    it('should return null without video', () => {
+      const controller = new VideoMediaPlayerController(createLitElement(), () => null);
+
+      expect(controller.getPIPElement()).toBeNull();
+    });
+  });
 });