feat: implement rlp Decodable and Encodable traits for Signature

[tcoratger]

Motivation

Signature should implement alloy_rlp::Encodable and alloy_rlp::Decodable traits.

Solution

Implementation of alloy_rlp::Encodable and alloy_rlp::Decodable traits for Signature with unit tests.

Should close #82.

PR Checklist

• Added Tests
• Added Documentation

[prestwich]

thank you for the contribution! there is some ongoing refactoring work to put the signature type in alloy-core, so some of this work may become part of that

[tcoratger]

thank you for the contribution! there is some ongoing refactoring work to put the signature type in alloy-core, so some of this work may become part of that

@prestwich Yes I saw that the issue was already linked to a big PR but as I saw that the signature aspect was not yet implemented on it, I told myself that I could open the specific PR for that.

Feel free to use this as you prefer.

[prestwich]

closing as superseded by alloy-rs/core#459, which now contains the tests