[REEF-1978] Adding Checkpoint handler for IMRU master

[jwang98052]

• Adding IMRUCheckpointHandler to handle task state persistent
• Added configuration module for IMRUCheckpointHandler
• Update IMRUJobDefination to all client to set checkpoint configuration
• Add UpdateTaskStateCodec implementation
• Update IMRU examples to set checkpoint config and call the check point handler
• Update test cases

JIRA: REEF-1978 This closes #

[jwang98052]

@markusweimer I have addressed your review comments.