Explode lines algorithm should not require valid geometries

This check isn't required for this algorith, and can get in
the way when using explode as a step prior for data cleaning

Author: nyalldawson

src/analysis/processing/qgsalgorithmexplode.cpp

@@ -105,6 +105,11 @@ QgsFeatureList QgsExplodeAlgorithm::processFeature( const QgsFeature &f, QgsProc
   }
 }
 
+Qgis::ProcessingFeatureSourceFlags QgsExplodeAlgorithm::sourceFlags() const
+{
+  return Qgis::ProcessingFeatureSourceFlag::SkipGeometryValidityChecks;
+}
+
 QgsFeatureSink::SinkFlags QgsExplodeAlgorithm::sinkFlags() const
 {
   return QgsFeatureSink::RegeneratePrimaryKey;

src/analysis/processing/qgsalgorithmexplode.h

@@ -48,6 +48,7 @@ class QgsExplodeAlgorithm : public QgsProcessingFeatureBasedAlgorithm
     QString outputName() const override;
     Qgis::WkbType outputWkbType( Qgis::WkbType inputWkbType ) const override;
     QgsFeatureList processFeature( const QgsFeature &feature,  QgsProcessingContext &context, QgsProcessingFeedback *feedback ) override;
+    Qgis::ProcessingFeatureSourceFlags sourceFlags() const override;
     QgsFeatureSink::SinkFlags sinkFlags() const override;
 
     std::vector< QgsGeometry > extractAsParts( const QgsGeometry &geometry ) const;