Support playground= features in map rendering

[matkoniecz]

this ideally would be done with some general though to make playground features distinguishable from general one (playground tunnel should not look like road tunnel)

maybe even playground= features can be made to be distinguishable from each other and in some way related to full-sized things (maybe tunnel can sort-of look like full tunnel? zip-wire share some styling with aerialway but be readily distinguishable?)

admittedly it is not a high-priority task

but should be nicely self-contained and likely requires no coding, just configuring some css
see https://github.com/openstreetmap/iD/pull/12141/changes for a much simpler PR doing some map rendering styling

Description

Currently playground=tunnel_tube playground=zipwire lines, playground=structure areas and so on get no special rendering

in fact such objects (unless mapped as nodes) are impossible to be distinguished from untagged objects or ones tagged by gibberish like hdjhdhdhjd=dsfhsfh

see say https://www.openstreetmap.org/way/908479256/history#map=19/52.474675/13.443175

Screenshots

which of lines is play tunnel, which is zipwire and which is untagged?

[matkoniecz]

for icons see openstreetmap/id-tagging-schema#2120 (comment) and related tasks

icons come from iD tagging schema