Add image verifier transfer service plugin system based on a binary directory

Signed-off-by: Ethan Lowman <ethan.lowman@datadoghq.com>

pkg/imageverifier/bindir/testdata/verifiers/large_stdout.go

@@ -0,0 +1,35 @@
+/*
+   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 main
+
+import (
+	"fmt"
+	"os"
+	"strings"
+)
+
+func main() {
+	n := 50000
+	fmt.Fprintf(os.Stderr, "attempting to write %v bytes to stdout\n", n)
+
+	wrote, err := fmt.Print(strings.Repeat("A", n))
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "got error writing to stdout: %v\n", err)
+	}
+
+	fmt.Fprintf(os.Stderr, "wrote %v bytes to stdout\n", wrote)
+}