Store crashing process name in sysprop

As part of Watchdog-triggered rollback logging, it would
be useful to know the service which has caused
updatable_crashing to be set. Store this in a new property
sys.init.updatable_crashing_process_name.

Test: manual
Bug: 138782888
Change-Id: Iffa38b2b746abbb5d823a8d69b7b8d2456836f4e