Tests for plugins repo

[daywalker90]

Hi, we'd like your tests for the cln plugin to run in the plugins repo so users can see in our new table if your plugin still works for the current cln version. Plugins without tests or failing tests will be moved to the archived section soon.

This project is a little special as usually we add the plugin as a submodule to the plugins repo and search it for tests to run. But since this repo contains the plugin in a sub-directory we need to get a little creative.

Good news is that i already tried your tests + very minor updates and they passed for cln 24.05! I'll open some PR's for that asap.

What we could really need are some release binaries for the cln plugin (and teos since its a dependency for the tests), because we really like to avoid compiling plugins in the plugins' repo CI.