[Berberis][CrashReporting] Dump guest thread info to tombstone file

As title.

Bug: b/321799516
Test: riscv64, checked tombstone file has wanted block.
https://paste.googleplex.com/5958508322750464
Added arm64 support and tested arm64 unwinding in internal repo.
https://paste.googleplex.com/6545612887818240

Change-Id: I4e8a3414d0198de88a577ef4d5672a9ad0286fc5