Improve Mapillary detection icons

[danieldegroot2]

This may be broken for me. It seems some detections do not have an icon and some may return a missing translation error.
I have also no idea how to check the web console for these elements as they can't be right clicked.

For https://www.openstreetmap.org/edit#map=20/52.65018/-7.24964

'General directions' sign detection at https://www.mapillary.com/app/?pKey=137639318388569&focus=photo

Traffic sign detection at [does not want to provide an image]

Sidenote: RapiD does not seem to show these empty icons.

[danieldegroot2]

Converted to issue #10500.