migrate to fastnear

[kobayurii]

This PR brings significant improvements to the read_rpc server after adding fastnear as an alternative data provider for NEAR Lake (near/near-lake-framework-rs#109).

Improvements to read_rpc Server:

• Leveraged the introduction of fastnear to optimize the read_rpc server.
• Simplified data processing logic of final and optimistic blocks, reducing latency and increasing throughput.
• Improved system to fetch blocks and chunks to enhance reliability and robustness, particularly in high-load scenarios.

These enhancements contribute to better overall performance of the read_rpc server, resulting in higher reliability, faster response times, and a more resilient system.