hostnamed: introduce new "embedded" chassis type

We really don't want to get lost in adding fridge, car, plane, drone, or
whatever else, hence add a generic term "embedded" cover all the cases
where the computer is just part of something bigger, and not at the
focus of things.

src/hostname/hostnamed.c

@@ -138,7 +138,8 @@ static bool valid_chassis(const char *chassis) {
                         "server\0"
                         "tablet\0"
                         "handset\0"
-                        "watch\0",
+                        "watch\0"
+                        "embedded\0",
                         chassis);
 }