Sync settings after installing the integration

[bkeepers]

If a repository already has a .github/config.yml, then the settings should be synced when the integration is installed.

This involves listening to the integration webhook events and then looking for a .github/settings.yml in all repositories that the installation is given access to.

[bkeepers]

It might also be interesting to automatically open a PR that adds all the current settings to .github/config.yml if the file doesn't already exist.

[knrt10]

@bkeepers I completed this. Please review my PR
Thanks in advance.

[stale]

Is this still relevant? If so, please comment with any updates or addition details.

[stale]

Is this still relevant? If so, what is blocking it? Is there anything you can do to help move it forward?