Created a dumpstate service.

For now this is still a limited service:

- It's only created when running an interactive bugreport.
- It only provides a listener to get updates.
- It will be just used by Shell to get updates.

Test: dumpstate_test passes
BUG: 31636879

Change-Id: Iae820261d220523c979bf905030456fcf0b2b618