Breaking change: Report HTML and JSON paths have changed

The HTML report used to be at build/reports/roborazzi/index.html but is now located at build/reports/roborazzi/<build_variant>/index.html. This is a first step toward fixing a long-standing issue where running recordRoborazzi (instead of recordRoborazziDebug) could break test results; further work is still needed to make it fully reliable.

You should be able to fix it by adding /debug/ (or your build variant) to the path in your CI script. I believe the change is straightforward, but if you run into any cases where it's difficult please let me know.

Note: This change does not affect the paths of the generated screenshot images, so most users will not be impacted.

Thank you for your contribution, @vladcudoidem!

Behavioral change: Fixed screenshot timing for Compose Preview Support

Previously, we used Espresso.onIdle() and ShadowLooper.idle(), but these APIs are not suitable for Compose. Consequently, screenshots could not be captured after onSizeChanged completed.

@Preview
@Composable
fun PreviewOnSizeChanged() {
  var size by remember { mutableStateOf("unknown") }
  Box(
    modifier = Modifier
      .size(100.dp)
      .background(Color.Blue)
      .onSizeChanged { size = "${it.width}x${it.height}" } // Now invoked! (It used to be skipped.)
  ) {
    Text(text = size, color = Color.White)
  }
}