Added ability for Docker containers to set usage of dns settings along with hostNetwork is true

Introduced chages:
   1. Re-writing of the resolv.conf file generated by docker.
      Cluster dns settings aren't passed anymore to docker api in all cases, not only for pods with host network:
      the resolver conf will be overwritten after infra-container creation to override docker's behaviour.

   2. Added new one dnsPolicy - 'ClusterFirstWithHostNet', so now there are:
      - ClusterFirstWithHostNet - use dns settings in all cases, i.e. with hostNet=true as well
      - ClusterFirst - use dns settings unless hostNetwork is true
      - Default

Fixes #17406

pkg/api/validation/validation.go

@@ -1788,12 +1788,12 @@ func validateRestartPolicy(restartPolicy *api.RestartPolicy, fldPath *field.Path
 func validateDNSPolicy(dnsPolicy *api.DNSPolicy, fldPath *field.Path) field.ErrorList {
 	allErrors := field.ErrorList{}
 	switch *dnsPolicy {
-	case api.DNSClusterFirst, api.DNSDefault:
+	case api.DNSClusterFirstWithHostNet, api.DNSClusterFirst, api.DNSDefault:
 		break
 	case "":
 		allErrors = append(allErrors, field.Required(fldPath, ""))
 	default:
-		validValues := []string{string(api.DNSClusterFirst), string(api.DNSDefault)}
+		validValues := []string{string(api.DNSClusterFirstWithHostNet), string(api.DNSClusterFirst), string(api.DNSDefault)}
 		allErrors = append(allErrors, field.NotSupported(fldPath, dnsPolicy, validValues))
 	}
 	return allErrors