Add User to Task

[Momro]

Checklist

• I have filled out the template to the best of my ability.
• This only contains 1 feature request (if you have multiple feature requests, open one feature request for each feature request).
• This issue is not a duplicate feature request of previous feature requests.
• I have read the "Important Note" section of the readme and this feature request fits the scope of the integration.

Is your feature request related to a problem? Please describe.

"It would be awesome to be able to attach a (or multiple) user to a task. This would allow create an automation that sends a notification to the user which is attached to the task to inform him/her about the due task."

(posted here: https://community.home-assistant.io/t/new-integration-home-maintenance-track-recurring-tasks-in-home-assistant/897324/22)

I think that might be handy for larger homes where you want to distribute tasks. I will think about adding this feature in a PR.

Describe the solution you'd like

add an optional selection for users that are currently present in the system

Describe alternatives you've considered

Use labels. But that requires adding all users as labels and violations DRY

Additional context

none