translate: support combined stream redirection and append

[seruman]

There are probably some obscure syntax not compatible that I've yet to know, but it seems like the below cases are supported in fish:

echo 123 > /dev/null 2>&1
echo 123 &> /dev/null
echo 123 &>> /tmp/null
echo 123 2>&1 > /dev/null
echo 123 >> /dev/null 2>&1
echo 123 2> /dev/null
echo 123 2>> /dev/null
echo 123 > /dev/null 2> /dev/stderr
echo 123 >> /dev/null 2>> /dev/stderr