[Feature] playwriter session delete-all

Trial and error often leaves me with many sessions that I no longer need.

I currently handle cleanup with this as an alias

playwright session list | awk 'NR>2 && $1 ~ /^[0-9]+$/ {print $1}' | xargs -r -n1 playwright session delete

It would be useful to support a built-in playwright session delete-all command so bulk cleaning up of sessions is easier and built-in.