Images (DataSources in KubeVirt language) need to be defined in Foreman (Compute Resource → Images tab).

As a user, I want Foreman to help me to select a DataSource, so I don't have to remember/copy&paste the name from somewhere else.

Right now the input field is a regular text-input without any data suggestion. To improve this, we could query the available DataSources from KubeVirt and provide a dropdown with the known ones.

As the DataSources can live in a different namespace, we should allow for overriding the dropdown values, just like we do in the network selection (see SAT-41356 for details).

Acceptance Criteria:

• existing DataSources are provided in a dropdown/autocomplete field
• users are not limited to the discovered DataSources (so they can reference those from other namespaces)
• when using an "unknown" (foreign) DataSource, editing an existing image doesn't reset the DataSource to a "known" one

Open questions:

• If you add a list of images in Foreman's front end, does the API also limit the selection of images to that list?