Stop using github.com/pkg/errors

[vanjiii]

How to categorize this issue?

/kind enhancement /priority 3 /platform kubevirt

What would you like to be added: Similar to gardener/gardener#4280 we should be using Go native error wrapping (available since GO 1.13).

grep -r '"github.com/pkg/errors"' | grep -v vendor/ | cut -f 1 -d ':' | cut -d '/' -f 1-3 | sort | uniq -c | sort
      1 cmd/gardener-extension-admission-kubevirt/app
      1 pkg/admission/decode.go
      1 pkg/apis/config
      1 pkg/cmd/config.go
      1 pkg/controller/controlplane
      1 pkg/controller/healthcheck
      1 pkg/controller/infrastructure
      1 pkg/kubevirt/client_factory.go
      1 pkg/kubevirt/data_volume.go
      1 pkg/kubevirt/network.go
      1 pkg/kubevirt/util.go
      1 pkg/webhook/controlplane
      1 pkg/webhook/controlplaneexposure
      3 pkg/admission/validator
      3 pkg/apis/kubevirt
      5 pkg/controller/worker

Why is this needed: Getting rid of vendors in favor of using stdlib is always nice. Others seem to do this as well - kubernetes/kubernetes#103043 and containerd/console#54.