Return a ContactManager to access and manage all the contacts available on the device.
The MozContact interface is used to describe a single contact in the device's contact database.
The additionalName property is a list of any additional names (other than given names or family names) usable for the contact.
The anniversary property represents the anniversary date of the contact (which can be different than its birthday date).
The bday property represents the birthday date of the contact.
The category property is a list of all the different categories the contact is associated with.
The email property is a list of all the possible e-mails for the contact.
The genderIdentity property represents the actual gender identity of the contact (which can be different than its actual sex).