Extend manual test app functionality for Sandbox Activities

- Separate Activity handling in separate file which build the layout and
  handle events.
- Preload a WebView from the SDK Context (not WindowContext).
- Start a video in the webview to test media, sound and storage (caching).
- Test gyroscope sensor.
- Open a landing page.

Bug: 277973940
Test: run 'adb shell device_config put adservices
      sdksandbox_customized_sdk_context_enabled true'
      If no type of Banner Ad is vide, the passed video will run,
      otherwise the preloaded WebView will start.

Change-Id: I94aec1eb40560473ac2ca7fbf489ed1931e6e628
2 files changed