Move launch logic into ActionHandlers.

Add test.
Add RootsAccess interface to RootsCache (to faciliate testing).
Create a new TestEnv class that:
    * bootstaps basic data and dependencies
    * installs test executor so async tasks can be executed predictably.
    * instruments main thread to ensure AsyncTasks return results
      before we continue to make asserts.
Add new Lookup interface to provide improved semantics over j.u.f.Function.
Inject access to Provider specific Executors by way of Lookup.

Change-Id: I0fc71897a4cc40d26c5fa3ae3bb88bad7dbdcf5c