## What changes were proposed in this pull request?
Kafka partitions can be revoked when new consumers joined in the consumer group to rebalance the partitions. But current Spark Kafka connector code makes sure there's no partition revoking scenarios, so trying to get latest offset from revoked partitions will throw exceptions as JIRA mentioned.
Partition revoking happens when new consumer joined the consumer group, which means different streaming apps are trying to use same group id. This is fundamentally not correct, different apps should use different consumer group. So instead of throwing an confused exception from Kafka, improve the exception message by identifying revoked partition and directly throw an meaningful exception when partition is revoked.
Besides, this PR also fixes bugs in `DirectKafkaWordCount`, this example simply cannot be worked without the fix.
```
8/01/05 09:48:27 INFO internals.ConsumerCoordinator: Revoking previously assigned partitions [kssh-7, kssh-4, kssh-3, kssh-6, kssh-5, kssh-0, kssh-2, kssh-1] for group use_a_separate_group_id_for_each_stream
18/01/05 09:48:27 INFO internals.AbstractCoordinator: (Re-)joining group use_a_separate_group_id_for_each_stream
18/01/05 09:48:27 INFO internals.AbstractCoordinator: Successfully joined group use_a_separate_group_id_for_each_stream with generation 4
18/01/05 09:48:27 INFO internals.ConsumerCoordinator: Setting newly assigned partitions [kssh-7, kssh-4, kssh-6, kssh-5] for group use_a_separate_group_id_for_each_stream
```
## How was this patch tested?
This is manually verified in local cluster, unfortunately I'm not sure how to simulate it in UT, so propose the PR without UT added.
Author: jerryshao <sshao@hortonworks.com>
Closes#21038 from jerryshao/SPARK-22968.
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