TEST: Adding test for ImageToNoDataMaskFilter. Test is standalone and does not require ulages or baselines from OTB-Data

TEST: Adding test for ChangeNoDataFilter. Test is standalone and does not require ulages or baselines from OTB-Data

BUG: Fixing error in filter implementation: GenerateOutputInformation is called before BeforeThreadedGenerateData(), and this->GetFunctor()->m_Flags was therefore always empty

ENH: Adding functions in NoDataHelper to Read/Write no-data flags and values from/to MetaDataDictionary

ENH: Adding a new filter to change the no data value of the image (replaces the no data metadata, and all occurences in pixel values