Log more info on the status of the process_artifacts_combined job to
help with debugging, and exit with exitcode 1 if anything goes wrong
Test plan: Ran the workflow
[successfully](https://github.com/facebook/react/actions/runs/3595185062)
Should hopefully be final tweaks! Sorry about all the noise.
Test plan: temporarily ran the workflow on this branch, verified output
in the builds/facebook-www branch is correct:
bfc0eb6cd4
This PR adds a new GitHub action to commit build artifacts for Facebook
into a new protected branch. This will later be used to setup an
automatic sync to www.
The hacky spinloop is meant to be a temporary implementation until we
can support running a script internally on top of the synced diff
(coming soon). A GitHub token is otherwise required if we want to setup
a pub/sub between cirleci and github but it's not straightforward to
provision one for our org. So this workaround should do for now since we
won't keep it around for too long.
Example of it running and creating a commit on the `builds/facebook-www`
branch:
https://github.com/facebook/react/actions/runs/3516958576/jobs/5894251359
