Registry not prefixed with k3d

[lindhe]

When creating a new registry, it sometimes gets prefixed with k3d (i.e. DefaultObjectNamePrefix) and sometimes not. This inconsistency should be fixed for a better user experience.

Running the following creates a registry called k3d-foo:

k3d registry create foo --port 127.0.0.1:1234 

Running the following creates a registry called foo:

k3d cluster create --registry-create foo:127.0.0.1:1234

The comment here says that "DefaultObjectNamePrefix defines the name prefix for every object created by k3d", which is clearly not true.

Clearly, the registry is created without the prefix when using k3d cluster create --registry-create:

k3d/cmd/cluster/clusterCreate.go

Line 578 in 72726ef

cfg.Registries.Create.Name = fvSplit[0]

Best would be if we could make DefaultObjectNamePrefix optional, because it can sometimes be nice to be able to override it (e.g. to create a local registry with the exact same name that a remote registry have).