path-util: add helper that checks if a path definitely refers to a dir

src/basic/path-util.h

@@ -201,6 +201,8 @@ bool valid_device_allow_pattern(const char *path);
 
 bool dot_or_dot_dot(const char *path);
 
+bool path_implies_directory(const char *path);
+
 static inline const char *skip_dev_prefix(const char *p) {
         const char *e;