Refactor CRI fuzzers

pkg/cri/sbserver/cri_fuzzer.go and pkg/cri/server/cri_fuzzer.go were
mostly the same.

This commit merges them together and move the unified fuzzer to
contrib/fuzz again to sort out dependencies. pkg/cri/ shouldn't consume
cmd/.

Signed-off-by: Kazuyoshi Kato <katokazu@amazon.com>

contrib/fuzz/cri_server_fuzzer.go

@@ -0,0 +1,47 @@
+//go:build gofuzz
+// +build gofuzz
+
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package fuzz
+
+import (
+	fuzz "github.com/AdaLogics/go-fuzz-headers"
+
+	"github.com/containerd/containerd"
+	criconfig "github.com/containerd/containerd/pkg/cri/config"
+	"github.com/containerd/containerd/pkg/cri/server"
+)
+
+func FuzzCRIServer(data []byte) int {
+	initDaemon.Do(startDaemon)
+
+	f := fuzz.NewConsumer(data)
+
+	client, err := containerd.New(defaultAddress)
+	if err != nil {
+		return 0
+	}
+	defer client.Close()
+
+	c, err := server.NewCRIService(criconfig.Config{}, client)
+	if err != nil {
+		panic(err)
+	}
+
+	return fuzzCRI(f, c)
+}