support IPROTO extended error info

Summary

• feat: support iproto extended error info

• fix: support error code in iproto response errors

• refactor: cleanup error::Encode -> EncodeError

• feat: TimeoutError alias & impl From for Error

• refactor: remove net_box::protocol module

• refactor: network::protocol::api::Request::decode_body(&self, buf) -> decode_response_body(buf)

• fix: network::Client::execute no longer takes a limit parameter

• refactor: cleanup protocol::Error, remove redundancy

• Rename protocol::Error -> ProtocolError
• Now it only contains iproto related errors, all the others are removed
• Now network::protocol::codec::* functions return crate::error::Error

• fix: used to crash in TarantoolError::error_type

• refactor: cleanup iproto constant definitions

Ensure that

• New code is covered by tests
• API is documented
• Changelog is up to date
• Version is bumped in the appropriate Cargo.toml files (already bumped)