[WIP] feat: Added Garnet Testnet

[blurpesec]

Description

Adds Garnet Testnet support (full support pending support by TheGraph).

Checklist:

• [ ] 1 PR, 1 purpose: my Pull Request applies to a single purpose
• [ ] I have commented my code, particularly in hard-to-understand areas
• [ ] I have updated the docs to reflect my changes if applicable
• [ ] I have added tests (and stories for frontend components) that prove my fix is effective or that my feature works
• [ ] I have performed a self-review of my own code
• [ ] If my code involves visual changes, I am adding applicable screenshots to this thread

Release Note Draft Snippet