Refactor Watchdog to dump interesting Java process stacks

The watchdog dumps native processes during ANRs. Additionally, it
dumps the following Java processes, itself (system_server) and the
com.android.phone process.

We now extend the 'interesting' native process concept to Java
processes.

This sets the stage to add the FUSE daemon, a Java process to the
interesting Java process list.

Test: Manually triggered watchdog event dumps FUSE daemon process
Bug: 149970494
Bug: 150525627
Change-Id: I0a49319617e05b79f80a87eba9adfeb6768bbd1e