[FLINK-10426] Port TaskTest to new code base

[FLINK-10426] (Part 1) testRegularExecution

[FLINK-10426] (Part 2) porting fails

1. testCancelRightAway
2. testFailExternallyRightAway
3. testLibraryCacheRegistrationFailed
4. testExecutionFailsInNetworkRegistration
5. testInvokableInstantiationFailed
6. testExecutionFailsInInvoke
7. testFailWithWrappedException
8. testCancelDuringInvoke
9. testFailExternallyDuringInvoke
10. testCanceledAfterExecutionFailedInInvoke
11. testExecutionFailsAfterCanceling
12. testExecutionFailsAfterTaskMarkedFailed
13. testCancelTaskException
14. testCancelTaskExceptionAfterTaskMarkedFailed

[FLINK-10426] (Part 3) partition state update tests

See also FLINK-10319, some of these tests would be removed based on that.

[FLINK-10426] (Part 4) watch dog

[FLINK-10426] (Part 4) config