Add configurability of synchronous and journal_mode for SQLite backed
Broker data stores. Setting these to synchronous=normal and journal_mode=wal
can significantly improve throughput at the cost of some durability in
the presence of power loss or OS crash. In the context of Zeek, this is
likely more than acceptable.
Additionally, add integrity_check and failure_mode options to support deleting
and re-opening a corrupted SQLite database at store creation.
Closes#2698
f35cf228dc