This patch just adds some more special folder locations to the File Browser, but ones that are not quite important enough to be shown in the System list. In a nutshell there are small number of folders that I would like to mark specially only if they are added to Favorites, are on the Recent list, or if you are just browsing in thumbnail view.

For this there is a new list added, FS_INTERNAL_PATH_CACHE, that can contain paths used for this purpose. And this cache is looked in when adding other entries or when browsing.

For all platforms the special folders added are for U.fontdir, U.textudir, U.pythondir, U.sounddir, U.tempdir.

For Windows this includes the root of all profiles, the new "3D Objects" profile folder, and Microsoft OneDrive.

Part of the reason for this patch is that the "Mac System List" patch requires this path cache idea and therefore this patch will bring that one down to a trivial 20 lines or so. And I am really wanting to get that one in for 2.83 so that we have feature parity between platforms.