Add containerd & gVisor support

This adds containerd, CNI, gVisor and all the necessary shims
and supporting infrastructure. It also enables all relevant features in
the Linux kernel. containerd is designed as a simple supervisor.Runnable.
It is not being started yet, this will happen in D497.

Split out from feature/kubelet.

Test Plan:
Has been tested in conjunction with the rest of D497, will be
covered by a K8s E2E test there.

X-Origin-Diff: phab/D509
GitOrigin-RevId: 92523516b7e361a30da330eb187787e6045bfd17
diff --git a/core/internal/containerd/ptp.json b/core/internal/containerd/ptp.json
new file mode 100644
index 0000000..d95da5d
--- /dev/null
+++ b/core/internal/containerd/ptp.json
@@ -0,0 +1,12 @@
+{
+  "name": "k8s-pod-network",
+  "cniVersion": "0.3.1",
+  "type": "ptp",
+  "mtu": 1420,
+  "ipam": {
+    "type": "host-local",
+    "subnet": "192.168.198.0/24",
+    "routes": [{ "dst": "0.0.0.0/0" }],
+    "dataDir": "/containerd/run/ipam"
+  }
+}