Add creation timestamp to LittleFS directories

Partial fix #9120.  This is simple enough to include and does not increase
the amount of flash writes on file updates significantly (which a
modified-time 't' attribute would).

libraries/LittleFS/src/LittleFS.h

@@ -167,6 +167,14 @@ class LittleFSImpl : public FSImpl
             return false;
         }
         int rc = lfs_mkdir(&_lfs, path);
+        if ((rc == 0) && _timeCallback) {
+            time_t now = _timeCallback();
+            // Add metadata with creation time to the directory marker
+            int rc = lfs_setattr(&_lfs, path, 'c', (const void *)&now, sizeof(now));
+            if (rc < 0) {
+                DEBUGV("Unable to set last write time on '%s' to %ld\n", path, (long)now);
+            }
+        }
         return (rc==0);
     }