No feedback when trying to save Institutions without a role

**Describe the bug**

When trying to save an Institution without any role selected the save button is clickable but does nothing.
There is no feedback for the user provided why it does nothing.

**To Reproduce**

Steps to reproduce the behavior:
1. Add Institution
2. Click on "save"

**Expected behavior**

Version1:
* role selection is marked as mandatory
* save button is not clickable

Version2:
* role selection is marked as mandatory
* save button is clickable
* there is visual feedback that draws your attention to the mandatory fields

**Screenshots**


**Desktop (please complete the following information):**
- OS: Kubuntu 20.04
- Browser Mozilla Firefox 86.0.1

**Smartphone (please complete the following information):**
not tested

**Additional context**
none

No files or tests are named. Start by reproducing the issue with Add Institution and Save without selecting a role, then locate the Institution form and its validation path; done means the role requirement is visibly communicated and the save behavior matches one of the proposed versions.

Written by the indexing model from the issue text.