feat(consumergroup): add consumer group commands

[craicoverflow]

Closes #384 #583 #537 #386

List

❯ ./rhoas kafka consumergroup list

  CONSUMER GROUP ID        ACTIVE MEMBERS   PARTITIONS WITH LAG  
 ------------------------ ---------------- --------------------- 
  console-consumer-86735                4                     1 

Describe

❯ ./rhoas kafka consumergroup describe --id console-consumer-86735

ACTIVE MEMBERS: 4        PARTITIONS WITH LAG: 1

  MEMBER ID (4)                                                            PARTITION   TOPIC     LOG END OFFSET   CURRENT OFFSET   OFFSET LAG  
 ------------------------------------------------------------------------ ----------- --------- ---------------- ---------------- ------------ 
  consumer-console-consumer-86735-1-809fe491-aeb3-4e04-a0b5-204f3a4a0da9           0   topic-3                0                0            0  
  consumer-console-consumer-86735-1-809fe491-aeb3-4e04-a0b5-204f3a4a0da9           1   topic-3                1                0            1  
  consumer-console-consumer-86735-1-809fe491-aeb3-4e04-a0b5-204f3a4a0da9           2   topic-3                0                0            0  
  consumer-console-consumer-86735-1-809fe491-aeb3-4e04-a0b5-204f3a4a0da9           3   topic-3                0                0            0  

Verification Steps

1. Create a Kafka instance.
2. Create a topic "topic-1" with 5 partitions.
3. Produce messages with an external tool like the kafka bin scripts.
4. Consume messages from it using the same tool.
5. Run the rhoas kafka consumergroup {list|describe|delete} commands to exercise functionality.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation change
• Other (please specify)

Checklist

• Documentation added for the feature
• CI and all relevant tests are passing
• Code Review completed
• Verified independently by reviewer

[craicoverflow]

@rkpattnaik780 I have found from the Cobra docs that you can use dynamic completions for flags!! So I have reverted to use --id here.

https://github.com/spf13/cobra/blob/master/shell_completions.md#specify-dynamic-flag-completion

[rkpattnaik780]

Great one!