chore: add editorconfig for TOML

[Br1ght0ne]

EditorConfig is probably the easiest way to keep whitespace changes low in most editors (without implementing consistent automatic TOML formatting), and makes commits like 1aa04a3 not happen :)

Checklist

• [ ] I have linked to any relevant issues.
• [ ] I have updated the documentation.
• [ ] I have added tests that prove my fix is effective or that my feature works.
• [ ] I have added necessary labels.
• [ ] I have done my best to ensure that my PR adheres to the Fuel Labs Code Review Standards.
• [ ] I have requested a review from the relevant team or maintainers.