Deprecate BuildListener#buildStarted and Gradle#buildStarted Registering this callback within an init, settings or build script has no effect as the build is already started. Those callback are also part of an older API. Removing it from the public API will prevent further user confusion.
Serialize the contents of `ArtifactCollection` instances to the instant execution cache. With this change, up-to-date `assembleDebug` builds work for the Santa Tracker sample and the simple test build.