Support for KIP-664: Admin API for detecting and aborting hanging transactions

[mlongob]

KIP-664 adds Admin API tooling to interact with the transaction system in Kafka. The useful Admin requests are:

• ListTransactions: Lists active transactions across all brokers with filtering by state, producer ID, duration, and transactional ID pattern.
• DescribeTransactions: Describes detailed transaction state including topics/partitions involved, producer epoch, and timing information.
• DescribeProducers: Retrieves active producer state from partition leaders including producer ID, epoch, sequence numbers, and transaction offsets.
• AbortTransaction: Aborts hanging transactions by writing abort markers via the WriteTxnMarkers API. Takes producer state from DescribeProducers to construct the abort request.

I've implemented this in #5496