Add roleTemplates in Rancher to view/manage sriovnetworks

In extension to !2230 (merged) we should introduce default roleTemplates to view / manage the resource sriovnetworks (in API group sriovnetwork.openshift.io), in similar way to what was done for networkattachmentdefinitions.

Only useful when SR-IOV network operator is enabled, but it should not harm to have those roleTemplates always defined.