audio: retrieve AIDL audio hal pids

Add support to get pids of AIDL based audio hals.
AudioService will set these pids to AudioFlinger, which
will be later used by Timecheck module to send signal to
these HALs to dump tombstones in case of Timecheck timeout.

Bug: 296959577
Test: check logs and check if aidl hal receives signal 35 on Timecheck.
(cherry picked from https://android-review.googlesource.com/q/commit:f8eb5364e8d9d1514cff271cb5aede6157770d52)
Merged-In: I3438da32f9bf8eecc26f89d1d9f5fbd996c3b92d
Change-Id: I3438da32f9bf8eecc26f89d1d9f5fbd996c3b92d