add operator:signed=no option to "Add operator for old clothes container quest"

[wurzel-3]

Use case

I encountered some containers which where not signed, which generated a lot of notices from unexperienced Streetcomplete users when encountering this situation without this option

Proposed Solution

Add an operator:signed=no option to the "Add operator for old clothes container quest"

[wurzel-3]

#570

[mnalis]

There are more than 250 (hit the limit) notes about that quest, many of which seems to be about operator:signed=no (I've hit a few by random picks), so it's probably time to revisit that comment from #570:

Also, probably an operator:signed=no option must be added for cases where it is not signed. (We could start without that option and see if many notes pop up)