fix: fetch credential logo URI from logo.uri

[nanderstabel]

Description of change

#301 already fixed that the Credential Issuers logo is fetched from logo.uri (instead of logo.url).

This PR does the same for the individual Credential logo's.

Before:

After:

Links to any relevant issues

• fix: use "uri" instead of "url" when reading display properties #300

How the change has been tested

Tested manually against https://staging.client.ngdil.com/demo

Definition of Done checklist

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• I have added tests that prove my fix is effective or that my feature works
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