Allow safe status only with set identifier

[scheidelerl]

Expected Behavior
Only if an identifier has been set as preferred should it be possible to set a list item to safe.

Current Behavior
A list item can be set to safe without an identifier being set as preferred.

Possible Solution
Implement the condition

Steps to Reproduce

1. Search for an identifier (Auto-Search or adding manually)
2. Find the right identifier (via Card-View or check the displayed information when hovering over the button with the cursor.)
3. Set the right identifier as preferred
4. If it is certain that the identifier is the correct one, select the safe status.