AudioService: communicate audio HAL process pids to native audioserver

Retrieve audio HAL processes pids from service manager and send them
to AudioFlinger native service. This is needed to dump audio HAL process tombstones
and because audioserver process does not have the SELinux permission to
list services.

Bug: 141528385
Test: Force watchdog and verify tombstone creation
Change-Id: I3e35b8040779e041b8d8c2e72d1e650d6f8fe818
Merged-In: I3e35b8040779e041b8d8c2e72d1e650d6f8fe818