Remove thiserror and ordered-float crates

[sile]

Copilot Summary

This pull request includes several changes to improve error handling and modify the Float struct in the Rust codebase. The most important changes include removing the thiserror dependency, implementing custom error handling for DecodeError and EncodeError, and updating the Float struct to ensure consistent hashing and equality checks.

Error handling improvements:

• src/codec.rs: Removed the thiserror dependency and implemented custom Display and Error traits for DecodeError and EncodeError enums.

Codebase simplification:

• Cargo.toml: Removed the thiserror dependency.

Float struct modifications:

• src/lib.rs: Added PartialEq derive to Float struct.
• src/lib.rs: Removed manual PartialEq implementation for Float and updated Hash implementation to handle special cases like NaN and zero values.