This change adds in a new rpc that we probably should swap to for the
underlying implementation of a couple rpcs we currently have. This new
rpc simply writes to an existing or new file some data. This is useful
for guest (and container) setup for things like /etc/hosts,
/etc/resolv.conf, writing to one-off cgroup files and so on.
Currently I've just implemented subtree_control toggling for the root cg
in standardSetup with this new change, but in the future I'd like to
swap the implementations of our /etc/hosts and /etc/resolv.conf logic
with this.
Closes#206
Much like we have support for supplying DNS configurations and writing
out /etc/resolv.conf, this adds a way to write out /etc/hosts for a
given container.
This allows the user the ability to raise an EOF for the containers
stdin. Today there's no way to close stdin so something as simple as
"cat" and relying on EOF to move the process forward doesn't work