feat: adding plugin for avalanchego

[embtools]

Summary

Adding plugin for avalanchego, an Avalanche node server

This differs from the avalanche plugin which is the developer tool, not the server itself

Description:

• Tool repo URL: https://github.com/ava-labs/avalanchego
• Plugin repo URL: https://github.com/embtools/asdf-avalanchego

Checklist

• Format with scripts/format.bash
• Test locally with scripts/test_plugin.bash --file plugins/<your_new_plugin_name>
• Your plugin CI tests are green
  • Tip: use the plugin_test action from asdf-actions in your plugin CI

[jthegedus]

Thanks :)