Save deep URL to email for task created from mail

[ChristophWurst]

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

As a Nextcloud I create tasks from my emails. When looking at the task later on I might need to check the email for context. I need to look up the email.

Describe the solution you'd like

Link to the email in the task.

This should only be done for owned calendars. For shared calendars someone else without access to my emails would see an unusable URL.

Describe alternatives you've considered

N/a

Additional context

Suggested by Daphne