Register QgsFeatureIds metatype

Fixes warnings when using signals which use this type, like
QgsVectorLayer::selectionChanged

src/core/qgsapplication.cpp

@@ -147,6 +147,7 @@ void QgsApplication::init( QString profileFolder )
   qRegisterMetaType<QgsProcessingFeatureSourceDefinition>( "QgsProcessingFeatureSourceDefinition" );
   qRegisterMetaType<QgsProcessingOutputLayerDefinition>( "QgsProcessingOutputLayerDefinition" );
   qRegisterMetaType<QgsUnitTypes::LayoutUnit>( "QgsUnitTypes::LayoutUnit" );
+  qRegisterMetaType<QgsFeatureIds>( "QgsFeatureIds" );
 
   QString prefixPath( getenv( "QGIS_PREFIX_PATH" ) ? getenv( "QGIS_PREFIX_PATH" ) : applicationDirPath() );
   // QgsDebugMsg( QString( "prefixPath(): %1" ).arg( prefixPath ) );