Add support for Github's native error message

### Describe the desired feature

Github has a native way for tools like linters to emit errors and display them on PRs. Need to investigate the difference between the sarif output and this as well as if it's beneficial for private repositories.

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

Start by locating Slither's existing SARIF output implementation and compare it with GitHub's linked workflow-command documentation. Determine the required native error-message behavior and whether private repositories change the recommendation; done means the supported behavior and its coverage are established.

Written by the indexing model from the issue text.