Enable proper testing of drag & drop interaction

[BenHenning]

After some investigation, I realized that drag & drop can't be correctly tested on Robolectric due to a couple of issues:

1. Robolectric shadows ViewGroup's requestDisallowInterceptTouchEvent and onInterceptTouchEvent, both of which are essential for ItemTouchHelper to process a stream of touch events simulating drag. I don't think this issue is hit with DragDropTestActivityTest (which does pass in Robolectric) because the latter doesn't use data-binding, and the view hierarchy is much simpler. The solution is to update ShadowViewGroup to call forweard to the real intercept touch event methods.
2. With larger views (such as drag & drop in StateFragment), moving these around can trigger ItemTouchHelper to think it should enable auto-scroll. Auto-scrolling results in Robolectric entering an infinite loop.

(1) requires a fix to Robolectric, whereas (2) can be solved by introducing our own simple Shadow:

import org.robolectric.annotation.Implementation;
import org.robolectric.annotation.Implements;

@Implements(className = "androidx.recyclerview.widget.ItemTouchHelper",
isInAndroidSdk = false, minSdk = 19, maxSdk = 29)
public final class ShadowTouchItemHelper {

  @Implementation
  protected boolean scrollIfNecessary() {
    // Never scroll while dragging since this can put Robolectric into an infinite loop. Prefer to
    // let the test fail, instead.
    return false;
  }
}

[BenHenning]

/cc @aggarwalpulkit596

[yurilev]

Possibly relevant: #1769 (comment)