Snapshot event log files to support incremental reading

This issue tracks the effort on snapshotting the current status of KVStore/AppStatusListener and enable incremental reading to speed up replaying event logs.

This issue will be on top of SPARK-29111 and SPARK-29261, as SPARK-29111 will add the ability to snapshot/restore from/to KVStore and SPARK-29261 will add the ability to snapshot/restore of state of (SQL)AppStatusListeners.

Note that both SPARK-29261 and SPARK-29111 will not be guaranteeing any compatibility, and this issue should deal with the situation: snapshot version is not compatible with SHS.