Save Code Now does not work for GitHub origins while GitHub's API is unavailable

GitHub's API can be unavailable for various reasons (upstream is unavailable, temporary network failure, blocked by a firewall, blocked by local policies such as being a third-party XHR, ...)

When this happens, the Save Code Now form should either report an error, or submit the request to the server anyway.

Migrated from T4055 (view on Phabricator)

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information