Enforce valid email address for User email

[harminius]

resolves #2537

Add additional format validity check for the user's email.

• when the validation registration form
• on the database level

Registration form check

Before running the migration, we need to sanitize our database.

To see which emails break the new rule, try select email from public."user" where email !~ '^[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+.[A-Za-z]{2,}$';