Support browsing TLS enabled regsitries without authentication configured

[ghost]

Is your feature request related to a problem? Please describe.
Using our RM extension to browse a registry with TLS & without auth I get an invalid configuration screen. When I configure it to use TLS with skip certificate verification I would expect this to then be valid, however I get an invalid configuration error. Seemingly this is not supported.

Describe the solution you'd like
Support this use case.

Additional context
I can deploy a registry with TLS and without auth credentials and am able to use the API via curl. E.g. curl -X GET https://testing.portainer.io:443/v2/_catalog will return a response of {"repositories":[]}.