RPC service

[aloknerurkar]

Part of #676

RPC service is a proxy JSON-RPC endpoint provided to clients. This service will intercept all the RPC calls from the client. The service will override certain RPCs to demonstrate use-case of preconfs as a seamless integration with other service providers (Wallet/Bridge etc). The other RPCs will be proxied out to public RPC providers or private nodes managed by the service.

1. The first step is user registration. For this the user will need to issue a EIP 7702 authorization to our smart contract on L1 to authorise funds for the bidding process. EIP 7702 authorization #679
2. The RPC service will keep track of events emitted from this contract to maintain balances of the users. This will be updated in a database and used for the bidding process.
3. When the user wants to send transaction for preconfirming, the RPC will intercept the transaction and check the funds in the gas tank for users and bid based on user configuration. Preconf combiner #678

[aloknerurkar]

Completed with #688 #710