Design doc

https://docs.google.com/document/d/17eh5NqX-Ktmk3trV3ICVRVKdu7IG667lIZOwhhqQNag/edit?tab=t.0

Description

This is a design for a test app that Android manufacturers can use to validate their hardware and drivers against Flutter’s Impeller renderer.

Goals

• Users can just push and run an APK to a device and get a result whether Impeller works on their device’s hardware, drivers, etc.
• The tests must use the setup and output of "Android Instrumentation Framework" + JUnit to match existing workflows.
• The test apk needs to be incorporated into CI to make sure it doesn’t get broken.
• There needs to be a way to force the Vulkan or OpenGLES backend when the test is executed.