user-util: move homed/nspawn map UID_MIN/UID_MAX define into user-util.h

Let's have them at a common place, so that we have the ranges altogether
at a minimal set of places.

src/basic/user-util.h

@@ -12,6 +12,14 @@
 #include <sys/types.h>
 #include <unistd.h>
 
+/* Users managed by systemd-homed. See https://systemd.io/UIDS-GIDS for details how this range fits into the rest of the world */
+#define HOME_UID_MIN 60001
+#define HOME_UID_MAX 60513
+
+/* Users mapped from host into a container */
+#define MAP_UID_MIN 60514
+#define MAP_UID_MAX 60577
+
 bool uid_is_valid(uid_t uid);
 
 static inline bool gid_is_valid(gid_t gid) {