Support github action output format

[exussum12]

https://docs.github.com/en/actions/learn-github-actions/workflow-commands-for-github-actions#setting-an-error-message

This will leave comments inline with the offending code, the output option can be used to turn it on, may even detect github by default

[MGatner]

This would be a helpful feature to have. Not sure if this would be helpful or not, but I reckoned this to another project and here is the implementation: composer-unused/composer-unused#280