Ability to configure containerd config.toml

[deniseschannon]

Look at existing PRs to get it in:
#248
#264

[dnoland1]

Before changing containerd template, verified it was listening on port 10010:

root@k3s-node1:/var/lib/rancher/k3s/agent/etc/containerd# netstat -anp | grep 10010
tcp        0      0 127.0.1.1:10010         0.0.0.0:*               LISTEN      9936/containerd

Copied /var/lib/rancher/k3s/agent/etc/containerd/config.toml to config.toml.tmpl. Edited config.toml.tmpl and changed stream_server_port = "10011".
Restarted k3s. Confirmed containerd is now listening on port 10011:

root@k3s-node1:/var/lib/rancher/k3s/agent/etc/containerd# netstat -anp | grep 10011
tcp        0      0 127.0.1.1:10011         0.0.0.0:*               LISTEN      13906/containerd