Support subject:wikidata and subject:wikipedia for historic=memorial and tourism=artwork and information=board

[matkoniecz]

It is really popular to misuses wikipedia and wikidata tag for linking to depicted events.

See https://wiki.openstreetmap.org/wiki/Key:wikipedia#Secondary_Wikipedia_links

For example https://www.openstreetmap.org/node/4835533107 is not a synagogue burnt down by Germans (it is not existing anymore) but a memorial.

Unfortunately correct tagging using subject:wikipedia and subject:wikidata is currently not supported by iD - so iD strongly encourages invalid tagging.

For start subject:wikidata and subject:wikipedia can be shown as "Wikipedia entry about topic depicted here" on information=board an tourism=artwork

(it gets trickier with historic=memorial as it may include also graves)

replaces openstreetmap/iD#6093

[matkoniecz]

https://github.com/openstreetmap/id-tagging-schema/pull/455/files and https://github.com/openstreetmap/id-tagging-schema/blob/main/data/fields/wikipedia.json look like relevant for implementation, but here testing seems necessary

See #131 (comment) for the current hack to do this