The Checkpoint coordinator should have the functionality of both handling checkpoints and savepoints.
The difference between checkpoints and savepoints is minimal:
- savepoints always write the root metadata of the checkpoint
- savepoints are always full (never incremental)
The commonalities are large
- jobs should be able to resume from checkpoint or savepoints
- jobs should fall back to the latest checkpoint or savepoint
This subsumes issue https://issues.apache.org/jira/browse/FLINK-3397