(Scripts|Emacs/app)~ported eshell banner to a script

Instead of doing it all in Emacs lisp (which while pretty fun to
write, is not fun to execute outside of Emacs), I wrote a shell script
which generates the same banners, then just linked
+eshell/banner-message to it.

Scripts/.local/scripts/cowfortune

@@ -0,0 +1,5 @@
+#!/usr/bin/env sh
+
+cow=$(echo -e "default\ncower\nmoofasa\nmoose\nmutilated\nsatanic\nsheep\nsmall\ntux\nvader" | shuf | head -1)
+
+fortune | cowsay -f $cow