[ASTERIXDB-2506][STO] Checkpoint Datasets - user model changes: no - storage format changes: no - interface changes: yes
Details: - Add new config to specify dataset checkpoint interval and default its value to 10 minutes. - Flush datasets which were not flushed for the dataset checkpoint interval. - Run dataset checkpoint logic as part of the CheckpointThread. - Improve dataset async flush API to accept any LSM index predicate. - Cleanup exception handling in CheckpoinThread. - Add test case for dataset checkpoint.