* A new createopt textbox has been added to the parameters dialog for algorithms which exports to raster files.
* A new metaopt textbox has also been added to the Algorithm parameters dialog.
* Raster file format is detected from output filename extension.
* GdalUtils has been improved to correctly detect raster formats supported for creation.
* QFileDialog for output rasters now display only file filters for supported output raster file formats.
The previous naming was too easily confused with processing outputs.
Rename them to QgsProcessingParameterFileDestination, etc... to
make it clearer what they are used for.