Ledger object models

[LimpidCrypto]

High Level Overview of Change

Ledger object models

Adds ledger object models including the AMM object model.

Models in general

It is also an attempt to implement a general order for fields (models/mod.rs):

//! Order of models:
//! 1. Type of model
//! 2. Required common fields in alphabetical order
//! 3. Required specific fields in alphabetical order
//! 4. Optional common fields in alphabetical order
//! 5. Optional specific fields in alphabetical order

If agreed on the order:

• [ ] open a new issue for refactoring the other models

serde_with_tag

Moved the Helper to fn serialize and fn deserialize to avoid defining it multiple times in a file.

Context of Change

27

Type of Change

• [x] New feature (non-breaking change which adds functionality)

Test Plan

• [x] serialization tests
• [ ] deserialization tests

Future Tasks

Keep an eye on the XRPFees amendment. It could change how some fields are typed and/or named.

[LimpidCrypto]

Alright somehow it put all commits of develop branch in here. This is impossible to review. I will fix it and open a new PR