Improve handling for email addresses in Dynamic Recipients feature

[kjmartens]

Improve the Dynamic Recipient feature to allow for various ways to handle email notification sending.

    {{ form.openTag({
        dynamicRecipients: {
            oneRecipient: {
                template: "express_forms_demo_notification.twig",
                map: {
                    first: {
                        to: "[email protected]", 
                        bcc: "[email protected], [email protected]"
                    },
                    second: "[email protected]",
                    third: {
                        cc: ["[email protected]", "[email protected]"]
                    },
                },
            }
        }
    }) }}