Missing multipolygon role check

[mdk]

If a multipolygon relation contains an inner inside an inner area, this is an error, but the validator did not complain about it.

In the attached example, the wood has the role "inner" in the forest MP. But it should be inner of the missing lake MP, which is inner of the forest). Or the wood should have no role. But for the example the validator should complain "Role mismatch: 'wood' is inner of an other inner."

[mdk]

Multipolygon with two inner, where one inner is (wrongly) inside an other inner.

[simon04]

In 6575/josm:

fix #7196 - Validator: add multipolygon role check

This is done by creating a new multipolygon using the logics from
"Create multipolygon" and see if the roles match.