feat: Add migration backfill for mptoken_issuance_history

[BryanJ1ang]

Note: this PR depends on previous ETL indexing PR here

Summary

Adds MPTTransactionHistoryMigrator, a Cassandra migration that backfills historical MPT issuance transaction history into the new MPT index tables:

• mptoken_issuance_transactions
• account_mptoken_issuance_transactions

The migrator full-scans the transactions table, reuses the live ETL MPT extractor, writes the same deterministic index rows produced by live indexing, and waits for queued async writes before marking the migration as complete.

Details

• Registers MPTTransactionHistoryMigrator with the Cassandra migration manager.
• Uses migration scan settings for full-table scanning:
  • migration.full_scan_threads
  • migration.full_scan_jobs
  • migration.cursors_per_job
• Adds Cassandra driver paging support so token-range scans read all result pages.
• Makes migration scans select explicit columns instead of relying on table column order.
• Propagates full-table scanner worker failures so failed scans do not get marked migrated.
• Keeps the migration non-blocking for Clio startup.

Testing

Added coverage for:

• Migrator status before and after running.
• Backfilling MPT issuance create paths and multi-issuance transaction fan-out.
• Idempotent reruns.
• Empty transaction tables.
• Parity between migration backfill rows and live ETL rows.
• Failed transactions with explicit MPT issuance references.
• Cassandra paging across more than one driver page.
• Full-table scanner validation and worker error propagation.