FEATURE: add a hidden setting that enables using email as a source for username suggestions (PR #14623)

This is a follow-up to FEATURE: stop using email as source for username and name suggestions for Single Sign On by AndrewPrigorshnev · Pull Request #14541 · discourse/discourse · GitHub. This adds a hidden setting for restoring the old behavior for those users who rely on it. We’ll likely deprecate this setting at some point in the future.

GitHub

LGTM

We’ll likely deprecate this setting at some point in the future.

I assume this is the reason why it’s a hidden setting, correct?

I assume this is the reason why it’s a hidden setting, correct?

Yes, exactly.