File chooser should use the selection mode of the filter if there is only one filter
Description
If only a single file filter is defined for a format reader plugin the file chooser should use the file selection mode of the file filter. Otherwise, it is always set to Files_Only.
If only a single file filter is defined for a format reader plugin the file chooser should use the file selection mode of the file filter. Otherwise, it is always set to Files_Only.