Write end to end testing harness for loading sqlite

[markstory]

• Create a topic with 64 partitions
• Generate a backlog of tasks
• Start up 4-16 consumers
• While consumers are running, kill consumers to trigger rebalances.
• Ensure that all queued tasks were stored in Sqlite dbs.

Example

• append 10000 tasks, 4 consumers. Even with kills/restarts all tasks should be stored in sqlite.