programs: xdg-terminal-exec: move to gui programs

hosts/common/programs/assorted.nix

@@ -164,7 +164,6 @@ in
       # "unar"
       "unzip"
       "wireguard-tools"
-      "xdg-terminal-exec"
       "xdg-utils"  # for xdg-open
       # "yarn"
       "zsh"

hosts/modules/gui/default.nix

@@ -63,6 +63,7 @@
       # "tokodon"
       "tuba"  # mastodon/pleroma client (stores pw in keyring)
       # "whalebird"  # pleroma client (Electron). input is broken on phosh.
+      "xdg-terminal-exec"
       "xterm"  # broken on phosh
     ];
   };