[split] Move xdg plugin to oh-my-fish/plugin-xdg

https://github.com/oh-my-fish/plugin-xdg

plugins/xdg/xdg.load

@@ -1,14 +0,0 @@
-# System
-set -x XDG_DATA_DIRS /usr/share /usr/local/share
-set -x XDG_CONFIG_DIRS /etc/xdg
-
-# User
-set -x XDG_CACHE_HOME $HOME/.cache
-set -x XDG_CONFIG_HOME $HOME/.config
-set -x XDG_DATA_HOME $HOME/.local/share
-set -x XDG_DESKTOP_DIR $HOME/Desktop
-set -x XDG_DOWNLOAD_DIR $HOME/Downloads
-set -x XDG_DOCUMENTS_DIR $HOME/Documents
-set -x XDG_MUSIC_DIR $HOME/Music
-set -x XDG_PICTURES_DIR $HOME/Pictures
-set -x XDG_VIDEOS_DIR $HOME/Videos