KAFKA-18555: Avoid casting MetadataCache to KRaftMetadataCache

[FrankYang0529]

The ZkMetadataCache is removed in https://issues.apache.org/jira/browse/KAFKA-18373. We should pull up the relevant methods so that no casting from MetadataCache to KRaftMetadataCache is required.

Add following methods to MetadataCache:

• getAliveBrokerEpoch
• isBrokerFenced
• isBrokerShuttingDown
• describeTopicResponse

Committer Checklist (excluded from commit message)

• Verify design and implementation
• Verify test coverage and CI build status
• Verify documentation (including upgrade notes)

[FrankYang0529]

@ijuma The only remaining casting is in DescribeTopicPartitionsRequestHandler. It uses KRaftMetadataCache#getTopicMetadataForDescribeTopicResponse. Do you think that we should either add it to MetadataCache or refactoring it to move related logic to DescribeTopicPartitionsRequestHandler? Or we can just keep it as current implementation? Thanks.

  val describeTopicPartitionsRequestHandler : DescribeTopicPartitionsRequestHandler = new DescribeTopicPartitionsRequestHandler(
    metadataCache.asInstanceOf[KRaftMetadataCache], authHelper, config)

[ijuma]

It's ok to pull up that method to MetadataCache, but we should take the chance and make it more concise. Instead of metadataCache.getTopicMetadataForDescribeTopicResponse, we can simply call it metadataCache.describeTopicResponse.