Concurrency

[iam047801]

1. Flatten tables: remove account data and message payloads
2. Internal messages now always have source and destination transactions
3. Introduce address labels with categories
4. Move data fetching logic from indexer service to fetcher
5. Fetch transactions and account states in multiple threads
6. Fetch blocks concurrently
7. Refactor get-methods execution logic to call every described get-method with no arguments