Filter function for dropdown list of users in an outbreak

[DanielCauchi]

Who requested this feature?

Daniel Cauchi - Scientific Officer Preparedness and Response at ECDC

###Feature Description.
When adding the follow up of a contact in an outbreak in Go.Data, one of the optional fields is to assign a user to follow up the contact. Clicking on this field displays a dropdown list of all the accounts (email addresses) on the Go.Data installation, including the email addresses of users who do not have access to that particular outbreak.
Similarly, in the outbreak settings under the “Teams” tab/function, a dropdown list that displays all accounts in the Go.Data installation is accessible.
This functionality is not in line with the need-to-know-principle of data protection. The necessity for external users to access the name and the e-mail address of all ECDC account holders is highly questionable and is certainly not a best-practice.

###Describe the solution you'd like
Ideally we would like to be able to adjust settings and include a filter so that the drop down list contains only email addresses of those people who already have access to that particular outbreak, independently of their role.

Acceptance Criteria

• Example
• Tested and reviewed
• Documented the changes in the approriate location
• Handed over to requester

Additional context

Add any other context or screenshots about the feature request here.

(Optional) Describe alternatives you've considered