Introduce User#lower_email for case insensitive email lookups

app/models/user.rb

@@ -109,12 +109,19 @@ def self.lookup_by_email(email)
  # often we have the most probably user object onhand. so use that if possible
  def self.lookup_by_lower_email(email, cache = [])
  email = email.downcase
- Array.wrap(cache).detect { |u| u.email.try(:downcase) == email } || find_by(['lower(email) = ?', email])
+ Array.wrap(cache).detect { |u| u.lower_email == email } || find_by(:lower_email => email)
  end
 
  singleton_class.send(:alias_method, :find_by_lower_email, :lookup_by_lower_email)
  Vmdb::Deprecation.deprecate_methods(singleton_class, :find_by_lower_email => :lookup_by_lower_email)
 
+ def lower_email
+ email&.downcase
+ end
+
+ virtual_attribute :lower_email, :string, :arel => ->(t) { t.grouping(t[:email].lower) }
+ hide_attribute :lower_email
+
  def lower_userid
  userid&.downcase
  end