Email visibility option

[Lan2u]

We don't consistently mask or not users emails.

Proposal: As a makespace member I want to choose if my email should be visible to other makespace members so I have control over who can contact me.

As an admin/super-user I want to be able to see all emails used by makespace members so I can send emails about important/safety issues in line with our privacy policy.

[Lan2u]

@chromy @erkannt thoughts on this one? Perhaps we should always mask for non-admins but sometimes I do want to message people privately / let them message me

[erkannt]

I like that. 'Show my email to other members' toggle?