Feature request: Notification channels restricted per user or per group or both.

[matli1965]

Suggest to implement certain notification channels to allow restriction of use for users and groups. For instance limit the SMS notification channel for use for a specific group of users only. This may also be applied to any another available notification channel.

Suggest:

Add attribute for the notification channel setting:

NEW 1.) Include user (all other users are excluded unless the user is an included user)
NEW 2.) Include group (all other groups/users are excluded unless they below to the included group)

Thank you for considering.
Chris