osbase/net/dhcp4c: move package out of metropolis

Move the dhcp4c package from metropolis/node/core/network/dhcp4c to
osbase/net/dhcp4c. The package is not specific to metropolis, and is
also used by nanoswitch and cloud/agent.

Change-Id: I508261c93c623d5b7a33a2089da11625b7a3abd0
Reviewed-on: https://review.monogon.dev/c/monogon/+/4565
Tested-by: Jenkins CI
Reviewed-by: Tim Windelschmidt <tim@monogon.tech>
diff --git a/metropolis/test/nanoswitch/nanoswitch.go b/metropolis/test/nanoswitch/nanoswitch.go
index c3fde27..78d8efe 100644
--- a/metropolis/test/nanoswitch/nanoswitch.go
+++ b/metropolis/test/nanoswitch/nanoswitch.go
@@ -29,9 +29,9 @@
 	"github.com/vishvananda/netlink"
 
 	common "source.monogon.dev/metropolis/node"
-	"source.monogon.dev/metropolis/node/core/network/dhcp4c"
-	dhcpcb "source.monogon.dev/metropolis/node/core/network/dhcp4c/callback"
 	"source.monogon.dev/osbase/bringup"
+	"source.monogon.dev/osbase/net/dhcp4c"
+	dhcpcb "source.monogon.dev/osbase/net/dhcp4c/callback"
 	"source.monogon.dev/osbase/supervisor"
 )