[FEATURE] GDN communication components

[mmorris44]

Feature

Create components needed to enable GDN communication in Mava. Create system using them.

Proposal

Need components to enable message passing during execution, as well as including them in the trainer step. Use jraph for GDN framework. Create a system with the components that uses a basic MPNN (like CommNet) and IPPO.

Definition of done

Should run and be able to solve easy Traffic Junction

Mandatory checklist before making a PR

• [ ] The success criteria laid down in “Definition of done” are met.
• [ ] Code is documented - docstrings for methods and classes, static types for arguments.
• [ ] Code is tested - unit, integration and/or functional tests are added.
• [ ] Documentation is updated - README, CONTRIBUTING, or other documentation.
• [ ] All functional tests are green.
• [ ] Link experiment/benchmarking after implementation (optional).