feat: trait RpcMethod for server, client, and schema

[aatifsyed]

Summary of changes

Iteration on #4033.

This approach obviates the need to define client operations separately:
https://github.com/ChainSafe/forest/blob/d0b490e7889157c668c1e3f4f96416fb093cf1c9/src/rpc_client/chain_ops.rs

In the limit, src/rpc_client can be deleted.

Obsoletes

• feat: chain-api generates OpenRPC definitions #4054, better to get this in first and then start rewriting handlers.

Tracking

• Forest OpenRPC FIPs #4038

Follow up work

• [tracking] RPC refactoring wishlist #4032
• client operations in a trait RpcEndpoint world #4066

Change checklist

• I have performed a self-review of my own code,
• I have made corresponding changes to the documentation,
• I have added tests that prove my fix is effective or that my feature works (if possible),
• I have made sure the CHANGELOG is up-to-date. All user-facing changes should be reflected in this document.

[lemmih]

Auto merge failed due to network error when connecting to ghcr.