IdP - Registration claims

[PhilipSkinner]

Add the ability to enable registration claims:

    "client_id": "interface-community-client",
    ...
    "features": {
        "registration": {
            "enabled": true,
            "claims" : [
                {
                    "name" : "first_name",
                    "label" : "Name",
                    "placeholder" : "your first name",
                    "type" : "text",
                    "required" : true,
                    "error_message" : "You must enter your first name."
                },
                {
                    "name" : "dob",
                    "label" : "Date of Birth",
                    "type" : "date",
                    "required" : true,
                    "error_message" : "You must enter your date of birth"
                },
                {
                    "name" : "title",
                    "label" : "Title",
                    "type" : "select",
                    "options" : [
                        {
                            "name" : "Mr",
                            "value" : "mr"
                        },
                        {
                            "name" : "Mrs",
                            "value" : "mrs"
                        }
                    ],
                    "required" : true,
                    "error_message" : "You must select a title"
                }
            ]
        }
    }
}```

Each of these claims is rendered on the registration screen for the client, collecting these default claims for a newly registered user.