live: validate rw access to image folder after remount

check that it is readable and writable

src/live/ogOperations.py

@@ -442,6 +442,11 @@ class OgLiveOperations:
                     raise ValueError('Target partition has no filesystem present')
 
             cambiar_acceso(user=self._smb_user, pwd=self._smb_pass)
+
+            if os.access(f'/opt/opengnsys/images', os.R_OK | os.W_OK) == False:
+                    logging.error('Cannot open /opt/opengnsys/images')
+                    raise ValueError('Cannot access image folder')
+
             ogCopyEfiBootLoader(disk, partition)
             ogReduceFs(disk, partition)