Fix error/validation message when adding permission

Error/validation message is not shown when leaving user/groups blank when adding new permission

Step to reproduce:
1. Open any Asset
2. Navigate to Permissions tab
3. Click on New button
4. Click on Create or Create and Add button without entering user or group info
5. Observe the screen

Actual Result:
User is not getting any required validation message when user clicks on Create button if user keeps blank user/group field.

Expected Result:
For better experience, user should get a warning message OR some kind of indication that the user/group field is required