nixos/cinnamon: Add x-cinnamon-mimeapps.list

This is specifically for https://github.com/linuxmint/nemo/blob/6.4.0/src/nemo-desktop-application.c#L398.

The same thing is already done in the GNOME module. Otherwise when you e.g try "Downloads" -> "Show in Folder"
in Firefox, it will just do nothing, this is probably not a good experience.

ref: https://salsa.debian.org/cinnamon-team/cinnamon-desktop/-/blob/debian/6.2.0-1/debian/x-cinnamon-mimeapps.list
ref: https://src.fedoraproject.org/rpms/cinnamon-desktop/blob/f41/f/x-cinnamon-mimeapps.list

nixos/modules/services/x11/desktop-managers/cinnamon.nix

@@ -135,6 +135,17 @@ in
       };
 
       environment.systemPackages = with pkgs; ([
+        # Teach nemo-desktop how to launch file browser.
+        # https://github.com/linuxmint/nemo/blob/6.4.0/src/nemo-desktop-application.c#L398
+        (writeTextFile {
+          name = "x-cinnamon-mimeapps";
+          destination = "/share/applications/x-cinnamon-mimeapps.list";
+          text = ''
+            [Default Applications]
+            inode/directory=nemo.desktop
+          '';
+        })
+
         desktop-file-utils
 
         # common-files