New feature: Opportunity to add weekly tasks/initiatives

[MargreteIversen]

As a user of Key results,
I would like the opportunity to add weekly activities/initiatives connected to each key result.
It should be possible to perform the following:

[MargreteIversen]

• Tag one or several owners of the activity
• One should be able to set the activities to be completed or archived at the end of the week.
• All members of a team should be able to add activities