docker(role): provide option to set up gVisor (runsc runtime)

roles/docker/templates/daemon.json.j2

@@ -0,0 +1,19 @@
+{
+    "log-driver": "journald",
+    "log-opts": {
+        "tag": "{{ '{{.Name}}' }}"
+    },
+    "ipv6": true,
+    "ip6tables": true,
+    "fixed-cidr-v6": "fd00:1::/64",
+    "default-network-opts": {
+        "bridge": {
+            "com.docker.network.enable_ipv6":"true"
+        }
+    }{% if docker__gvisor_setup %},
+    "runtimes": {
+        "runsc": {
+            "path": "/usr/bin/runsc"
+        }
+    }{% endif %}
+}