Reduce memory consumption for large folders

[Oliver-Loeffler]

With directories containing 100.000s of files memory consumption can be an issue.
For ~ 330.000 files on Windows 10 the FileChooserModel requires ~ 80 MiB of memory.
On macOS Monterey its ~ 40 Mib for 244.000 files.

As the FileChooser is used on systems where 300.000 files to 900.000 files are listed, reduced memory consumption should help to improve overall application performance.