util-lib: split out hex/dec/oct encoding/decoding into its own file

src/libsystemd-network/network-internal.c

@@ -30,6 +30,7 @@
 #include "dhcp-lease-internal.h"
 #include "log.h"
 #include "network-internal.h"
+#include "hexdecoct.h"
 #include "parse-util.h"
 #include "siphash24.h"
 #include "string-util.h"

src/libsystemd-network/sd-dhcp-lease.c

@@ -34,6 +34,7 @@
 #include "hostname-util.h"
 #include "in-addr-util.h"
 #include "network-internal.h"
+#include "hexdecoct.h"
 #include "parse-util.h"
 #include "unaligned.h"