Refactor rate limiting applied to network connections

[mohanson]

This pull request refactors how rate limiting is applied to network connections throughout the codebase. The previous custom RateConn wrapper is removed and replaced with a more idiomatic approach using Go's standard IO interfaces (io.TeeReader, io.MultiWriter) to enforce rate limits on both reading and writing. This change impacts several server and client implementations, simplifying the code and improving maintainability.

Rate Limiting Refactor:

• Removed the custom RateConn type and its associated methods from daze.go, eliminating a bespoke implementation for rate limiting connections.
• Replaced all usages of RateConn in server and client code (protocol/ashe/engine.go, protocol/baboon/engine.go, protocol/czar/engine.go, protocol/dahlia/engine.go) with the standard ReadWriteCloser struct, which now utilizes io.TeeReader and io.MultiWriter combined with rate.NewLimitsWriter for rate limiting. [1] [2] [3] [4] [5]

Code Consistency and Simplification:

• Updated the instantiation of ReadWriteCloser to consistently use pointers (e.g., &ReadWriteCloser{...}) across all affected files for proper interface implementation and resource management. [1] [2]

These changes collectively modernize rate limiting logic and simplify connection handling, making the codebase easier to understand and maintain.