fix: Correctly detect configuration for the webrtc-card live provider (#1850)

- Closes #1843

If this breaks something for you, please let me know. As a workaround,
you should manually be able to set it back to what it was with something
like:

```yaml
cameras:
 - camera_entity: camera.office
   webrtc_card:
      url: <frigate camera name>
```

tests/camera-manager/generic/engine-generic.test.ts

@@ -313,6 +313,20 @@ describe('GenericCameraManagerEngine', () => {
         },
       });
     });
+
+    it('for webrtc-card', () => {
+      expect(
+        createEngine().getCameraEndpoints(
+          createGenericCameraConfig({
+            camera_entity: 'camera.office',
+          }),
+        ),
+      ).toEqual({
+        webrtcCard: {
+          endpoint: 'camera.office',
+        },
+      });
+    });
   });
 
   it('should execute PTZ action', () => {