Warn when an import fails instead of silently ignoring them.
Without these it was impossible to tell whether a type was not resolved due to an unresolvable import or due to other reasons.
It also fixes the previous behavior of just dumping the types of qmltypes into the rootScope if manually imported.
Now they are only are present when actually importing one of the modules mentioned in the type's export statement.
Change-Id: I62bdd99828702ed02512eaac30f7f99b98d1df28
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
Maximilian Goldstein