feat: add setting to allow guests to change their email

[icewind1991]

occ config:app:set guests allow_email_change --value true --type boolean --lazy

to enable

[nc-enterprise-user]

Thank you for adding this flag.

If I may ask, are you aware of any specific concerns related to allowing Guests to change their email?

Is it just that there would be a disconnect between the Guest's static user ID and their email? Are there any other concerns related to Guests being able to change their emails or scenarios where there could be undesirable behavior?

We currently allow Guests to change their email, but the latest release makes me wonder if there could be considerations we are not aware of, or if it's just an administrative/organization preference.

Thank you, again.

[icewind1991]

If I may ask, are you aware of any specific concerns related to allowing Guests to change their email?

The issue was mainly around confusion with the email being different, or in some cases empty. Nothing fundamental that I'm aware of.