Enable one way github sync

If you enable v2 sync in the app, it'll setup a bi-directional sync. That means that from the app you can Save & Sync and it'll push back to github, and commits made to github will deploy to the app.

But it can be useful to restrict sync to only work one way - to deploy to multiple targets on commit.

I think the use-case is:

• I have a project at app.openfn.org which my developers use
• When I merge a sandbox with a new feature or fix into my main project, I want to sync back to github
• Github is connected to deployed projects running on-site at healthcare clinics
• When github received a commit on main, I want to deploy an update to all my connected sites
• I do NOT want someone to access an openfn instance on-site, make a change, and hit Save & Sync - which would update all my connected instances, including app.openfn.org and other live clinics.

I don't think the inverse use-case is true: I don't think you'd ever want to pull multiple app instances into a single repo. I can't make any sense of that in my little mind.

That would mean you can brand this as "deploy only" sync, or have a checkbox like "Enable Save & Sync for this project"

It's possible that this use-case shouldn't use github sync at all, and the on-site apps aren't aware they're synced. There's just a specially configured github action (possibly bespoke) which handles the sync on commit. OTOH this is all github sync is.

It would also be nice, in this use-case, to not have a GH action per connected project, but to have a single GH action which publishes to all connected apps (controlled by a list somewhere). This is a more github sync v2-ish thing though

No files, tests, or entry points are named. Start by reviewing the existing v2 GitHub sync and Save & Sync behavior, then compare it with the proposed deploy-only and multi-target GitHub Action options. Done should be a decided scope and an implemented one-way sync behavior with coverage for the selected configuration.