Running a sync locally #663

(This is related to #505, but probably an even simpler goal.)

Is there some simple way to run this via a command, without any of the server stuff, long-running cron server, webhooks, PR dry-runs, etc etc?

The thing is that all of these are probably nice to have for some people, but if the core sync functionality was available as a simple ./sync, then it would have a bunch of advantages:

• I would be able to run it locally and see what it does.
• Potentially with a GH token that is restricted in what it can do, so I feel calm not risking blowing up a whole org because of some brain fart.
• Then I would be able to run it, as asked in Run SafeSettings as Github Action #505 , from a cron-triggered workflow.
• And for stuff that are apparently out of scope (org settings? like managing org teams from a yaml spec), I could make safe-settings be part of an action that would do Other ThingsTM too.
• Best of all, I won't need to futz around with installing a GH app, which can come with a heavy bureaucratic cost (in a corp environment).

Or maybe I'm meowing at the wrong tree, and there's some core library used somewhere in here that does just the above? (Or anything similar in functionality and limited scope?)