✨ Set up Copilot instructions

[lahabana]

Configure instructions for this repository as documented in Best practices for Copilot coding agent in your repository.

Some useful place to learn how to write some code on this repo is in: https://github.com/kumahq/kuma/blob/master/DEVELOPER.md

especially make check make test make generate and make test UPDATE_GOLDEN_FILES=1