bin/ctr,integration: new runc-shim with failpoint

Added new runc shim binary in integration testing.

The shim is named by io.containerd.runc-fp.v1, which allows us to use
additional OCI annotation `io.containerd.runtime.v2.shim.failpoint.*` to
setup shim task API's failpoint. Since the shim can be shared with
multiple container, like what kubernetes pod does, the failpoint will be
initialized during setup the shim server. So, the following the
container's OCI failpoint's annotation will not work.

This commit also updates the ctr tool that we can use `--annotation` to
specify annotations when run container. For example:

```bash
➜  ctr run -d --runtime runc-fp.v1 \
     --annotation "io.containerd.runtime.v2.shim.failpoint.Kill=1*error(sorry)" \
     docker.io/library/alpine:latest testing sleep 1d

➜  ctr t ls
TASK       PID       STATUS
testing    147304    RUNNING

➜  ctr t kill -s SIGKILL testing
ctr: sorry: unknown

➜  ctr t kill -s SIGKILL testing

➜  sudo ctr t ls
TASK       PID       STATUS
testing    147304    STOPPED
```

The runc-fp.v1 shim is based on core runc.v2. We can use it to inject
failpoint during testing complicated or big transcation API, like
kubernetes PodRunPodsandbox.

Signed-off-by: Wei Fu <fuweid89@gmail.com>

cmd/ctr/commands/commands.go

@@ -116,6 +116,10 @@ var (
 			Name:  "label",
 			Usage: "specify additional labels (e.g. foo=bar)",
 		},
+		cli.StringSliceFlag{
+			Name:  "annotation",
+			Usage: "specify additional OCI annotations (e.g. foo=bar)",
+		},
 		cli.StringSliceFlag{
 			Name:  "mount",
 			Usage: "specify additional container mount (e.g. type=bind,src=/tmp,dst=/host,options=rbind:ro)",
@@ -239,6 +243,19 @@ func LabelArgs(labelStrings []string) map[string]string {
 	return labels
 }
 
+// AnnotationArgs returns a map of annotation key,value pairs.
+func AnnotationArgs(annoStrings []string) (map[string]string, error) {
+	annotations := make(map[string]string, len(annoStrings))
+	for _, anno := range annoStrings {
+		parts := strings.SplitN(anno, "=", 2)
+		if len(parts) != 2 {
+			return nil, fmt.Errorf("invalid key=value format annotation: %v", anno)
+		}
+		annotations[parts[0]] = parts[1]
+	}
+	return annotations, nil
+}
+
 // PrintAsJSON prints input in JSON format
 func PrintAsJSON(x interface{}) {
 	b, err := json.MarshalIndent(x, "", "    ")