IssueTracker

When we are unable to use artifact transforms directly (e.g. Firebase transform is applied), use artifact transforms to dex&desugar libraries. This means:
- we can remove custom Android build cache
- simply caching logic for external libs (this is provided by artifact transforms)

Current approach (ag/Iff39b1949a2f45258a7900bfb764acff9be5bf30) is to create a detached configuration, and to specify per-task artifact transform that captures all relevant parameters. In order to maintain backwards compatibility, if desugaring fails for some external library, we will retry processing in the task and desugar against entire runtime classpath.