feat: add tps metric to contracts table

[Larkooo]

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Summary by CodeRabbit

Release Notes

• New Features

  • Introduced subscription capabilities for indexer updates in the World service.
  • Added a new RPC method, SubscribeIndexer, allowing clients to receive updates related to the indexer.
  • Enhanced transaction processing tracking with new parameters in the set_head method.

• Improvements

  • Updated metadata handling to reflect new naming conventions and types.
  • Improved error handling and subscription management in the gRPC client and server.

• Database Changes

  • Added new columns last_block_timestamp and tps to the contracts table for enhanced transaction metrics.