SAMZA-2703: Add input stream partition count and input stream regex monitoring for refreshing job model

[cameronlee314]

Feature: For StaticResourceJobCoordinator, trigger job restart when input stream partition count changes or input stream regex set changes.

Changes:

1. Add pluggable JobRestartSignal interface for triggering a job restart.
2. Add StreamPartitionCountMonitor and StreamRegexMonitor to StaticResourceJobCoordinator for triggering a JobRestartSignal when input stream partition count changes or input stream regex set changes.

Tests:
Added some code into StreamPartitionCountMonitor which triggered the callback after 5 minutes and verified that the placeholder NoOpJobRestartSignal was called.

API changes (all backwards compatible):
Configure job.coordinator.restart.signal.factory to specify an implementation of JobRestartSignalFactory to use.

[mynameborat]

Looks good to me. Few minor comments.

[mynameborat]

Feel free to commit once the travis build pass.
Looks good to me.

[mynameborat]

Is the KafkaCheckpointIntegrationTest failure related to your change? As in, it is expecting one commit but got 2.

[cameronlee314]

Is the KafkaCheckpointIntegrationTest failure related to your change? As in, it is expecting one commit but got 2.

That test doesn't use this new job coordinator flow, so it is unrelated to this change. It didn't fail on the github actions CI build, so it is a flaky test. I'm not sure about the root cause of the flakiness, but I saw that there was a validation bug in that test which would have helped to debug it, so I fixed that (#1549). I'll investigate more if it comes up again.