Manual/automated testing of gradle plugin

[snowp]

The plugin introduced in #137 can be tested locally by publishing it to local Maven and adding a dependency locally from the test app, but this requires manual work and modifying the repo every time we want to test the code

We should

• Make it easier to perform manual testing against some app (not necessarily the gradle-test-app but could be)
• Figure out how to set up automated e2e testing that ensures that the plugin applies correctly to an android application