filechooser: Don't automatically select a file

filechooser: Don't automatically select a file

When the folder changes, do not select the first item in the list,
so if the user enters a folder and then clicks the accept button,
the current folder is returned instead of the selected one.
To maintain consistency with the previous implementation, when a
folder in the path bar is clicked the previously-entered folder is
selected, and when the file chooser is in open file mode the first
item is always selected.

See #5438