Event source Sink is not marked as required in create form

Description of problem:

When the user creates an event source the user should see an indicator if a field is required or not.

The form does not enable the submit button until a sink URI is entered. But the field is not marked as required.

Prerequisites (if any, like setup, operators/versions):

1. OpenShift Serverless operator (tested with 1.16.0)

Steps to Reproduce

1. Install Serverless operator and create required eventing / sourcing resources
2. Open Dev perspective
3. Open add page > select "Event source"
4. Select one of the sources (tested with ApiServerSource and PingSource)
5. Press Create... button on the overlay
6. Enter * * * * * as schedule

Actual results:

1. Form doesn't show a reason why the user can not create the event source.

Expected results:

1. Sink field should be marked as required.

When the resource or URI are required, I would recommend to mark the complete section as required. When Resource and URI would have an asterisk this could confuse the user, or?

Reproducibility (Always/Intermittent/Only Once):

Always

Build Details:

4.9 master (tested with commit 2031e8be8a7fe8d4549e0c2a8db061371fe8a4f9)

Additional info:

None