need_external_needs: No import of types unknow

[danwos]

need_external_needs does not import needs, if the needs in a given needs.json have need-types, which are not configured in the target project. In this case no need-elements get internally created.

We should be able to detect this and write log messages on the console for each need-element that could not be imported (incl. reason).

I'm not sure if there can be a mechanism to import needs, which have a different/unknown configuration.

[danwos]

This may be also relevant for needimport