lomiri.lomiri-session: Force xdg-user-dirs-update to be run

mediascanner2 expects xdg-user-dirs to be set up properly, otherwise its g_get_user_special_dir() calls fail.

Lomiri, by itself, doesn't seem to ensure this by default, so hack in a call of this.

pkgs/desktops/lomiri/data/lomiri-session/default.nix

@@ -13,6 +13,7 @@
   makeWrapper,
   pkg-config,
   systemd,
+  xdg-user-dirs,
 }:
 
 stdenvNoCC.mkDerivation (finalAttrs: {
@@ -34,6 +35,10 @@ stdenvNoCC.mkDerivation (finalAttrs: {
 
     substituteInPlace systemd/CMakeLists.txt \
       --replace-fail 'pkg_get_variable(SYSTEMD_USER_DIR systemd systemduserunitdir)' 'pkg_get_variable(SYSTEMD_USER_DIR systemd systemduserunitdir DEFINE_VARIABLES prefix=''${CMAKE_INSTALL_PREFIX})'
+
+    # Inject a call to xdg-user-dirs-update, so when mediascanner2 launches, it can actually scan for files
+    substituteInPlace desktop/dm-lomiri-session.in \
+      --replace-fail '@CMAKE_INSTALL_FULL_LIBEXECDIR@/lomiri-session/run-systemd-session' '${lib.getExe' xdg-user-dirs "xdg-user-dirs-update"} && @CMAKE_INSTALL_FULL_LIBEXECDIR@/lomiri-session/run-systemd-session'
   '';
 
   nativeBuildInputs = [