chore(websocket): Simplify error handling and improve code readability

[0x676e67]

This pull request includes several changes to the src/client/websocket/mod.rs and src/error.rs files to simplify error handling and improve code readability. The most important changes include consolidating error imports, refactoring error creation, and modifying error handling in the WebSocketResponse and WebSocket implementations.

Improvements to error handling and code readability:

• src/client/websocket/mod.rs: Consolidated imports from crate::error and moved pub use message::{CloseCode, CloseFrame, Message, Utf8Bytes}; to the top of the file.
• src/client/websocket/mod.rs: Refactored error creation in WebSocketRequestBuilder to use the new error::upgrade function.
• src/client/websocket/mod.rs: Modified WebSocketResponse to use error::upgrade for various error conditions, improving consistency and readability. [1] [2] [3]
• src/client/websocket/mod.rs: Updated Stream implementation for WebSocket to use error::body for error handling.
• src/error.rs: Added a new upgrade function for creating upgrade errors and removed the redundant upgrade function definition. [1] [2]