* The `EmailRecipientInterface` with `hasEmail():bool` and `getEmail():string`

methods was introduced.

* [BC BREAK] Added method `hasPhone():bool` to `SmsRecipientInterface`.

* Added `email` and and `phone` property to `Recipient`.

* [BC BREAK] The `Recipient` now implements `EmailRecipientInterface` and `SmsRecipientInterface`.

* [BC BREAK] The `NoRecipient` now implements `EmailRecipientInterface` and `SmsRecipientInterface`.

* [BC BREAK] Removed the `AdminRecipient`.

* [BC BREAK] Changed the type-hint of the `$recipient` argument in the `as*Message()`

of the `EmailNotificationInterface` and `SmsNotificationInterface` to `EmailRecipientInterface`

and `SmsRecipientInterface`.

* [BC BREAK] Changed the type-hint of the `$recipient` argument in the static `fromNotification()`

factory methods in `EmailMessage` and `SmsMessage` to `EmailRecipientInterface`

and `SmsRecipientInterface`.

* Changed `EmailChannel` to only support recipients which implement the `EmailRecipientInterface`

and have an email set.

* Changed `SmsChannel` to only supports recipients which implement the `SmsRecipientInterface`

and have a phone number set.

* [BC BREAK] The `ChatMessage::fromNotification()` method's `$recipient` and `$transport`

arguments were removed.

* [BC BREAK] The `EmailMessage::fromNotification()` and `SmsMessage::fromNotification()`

methods' `$transport` argument was removed.