CASSANDRA-21129: Offline TCM dump tool

[dracarys09]

When a Cassandra node fails to start due to Transactional Cluster Metadata (TCM/CEP-21) corruption or issues, operators need a way to inspect the cluster metadata state offline without starting the node. The existing tools (nodetool, cqlsh) require a running node, leaving operators blind when debugging startup failures.

With CEP-21 (Transactional Cluster Metadata), cluster metadata is stored in system tables:

• system.local_metadata_log - Contains transformation entries (epoch -> transformation)
• system.metadata_snapshots - Contains periodic snapshots of ClusterMetadata

When a node fails to start due to TCM corruption or inconsistencies, operators have no way to inspect the metadata state without a running node. This tool fills that gap by reading directly from SSTables.

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