Refactor and remove prost + tonic - #1131

Code Review

This pull request replaces heavy external dependencies like sui-rpc, prost, and tonic with a custom, lightweight Protobuf and gRPC implementation within the gem_encoding and gem_jsonrpc crates. It introduces new macros for message encoding/decoding and refactors the Sui and SuiNS clients to use these tools. The review feedback identifies critical issues where the custom implementation fails to correctly handle Protobuf oneof encoding, which will lead to server-side rejections. Additionally, the feedback points out a missing check for gRPC-specific status headers in the transport layer, potential overflow bugs in varint decoding, and opportunities to optimize memory allocations during byte field encoding.