[Feature Request] Separate sorting modes for files and folders

Perhaps something like this for the sorting menu:

Files
-------------------------
Name                 ( )
Type                 ( )
Size                 ( )
Last modified        ( )
Ascending            [ ]
-------------------------
Folders
-------------------------
Name                 ( )
Last modified        ( )
Ascending            [ ]
-------------------------
Folders first        [ ]
Only for this folder [ ]

Motivation here is to make "last modified" sorting on folders synchronized with Syncthing more usable: since Syncthing only syncs file modification times, not folder modification times, it makes the current unified "Last modified" sort order for folders somewhat hit-or-miss, often displaying them in whatever order Syncthing felt like creating the folders. Being able to sort files by "Last modified" and folders by "Name" would be much more usable for folders like "Photos" where I'd like the JPEGs in a folder sorted by modification time (so more recent files are near the top) but any nested folders by name.

Not entirely sure what should be done if "Folders first" is unchecked and the file & folder sorting are set to different things like "Size" and "Last modified". Perhaps grey-out/disable the folder settings when "Folders first" is unchecked so that can't happen? Or only show the new folder sorting options when "Folders first" is checked?

No files or tests are named. Start by locating the sorting menu and the code that orders files and folders; resolve the behavior when “Folders first” is unchecked, then verify independent file and folder criteria, direction, and per-folder persistence match the request.