Support for Generic JSON-RPC Protocols

Adding support for generic JSON-RPC protocols in eRPC, with essential features such as load balancing, fault tolerance, rate limiting, singleflight (to solve thundering herds), and monitoring.

This enable eRPC to be used for various purposes, domains, and use cases, such as:
• Other blockchain protocols like Bitcoin, Solana, and TON (making it possible to use eRPC for any blockchain by default)

• Non-blockchain JSON-RPC applications

• Custom JSON-RPC implementations

This improvement would make eRPC more universal and flexible solution for handling JSON-RPC traffic across a wide range of projects.