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/BUILD.bazel b/core/internal/containerd/BUILD.bazel
new file mode 100644
index 0000000..dd7cf6d
--- /dev/null
+++ b/core/internal/containerd/BUILD.bazel
@@ -0,0 +1,19 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
+
+go_library(
+    name = "go_default_library",
+    srcs = ["main.go"],
+    importpath = "git.monogon.dev/source/nexantic.git/core/internal/containerd",
+    visibility = ["//core:__subpackages__"],
+    deps = [
+        "//core/pkg/logbuffer:go_default_library",
+        "@org_golang_x_sys//unix:go_default_library",
+    ],
+)
+
+exports_files([
+    "config.toml",
+    "runsc.toml",
+    "loopback.json",
+    "ptp.json",
+])