Move content/local to plugins/content/local

Signed-off-by: Derek McGowan <derek@mcg.dev>

plugins/content/local/locks_test.go

@@ -0,0 +1,34 @@
+/*
+   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 local
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestTryLock(t *testing.T) {
+	err := tryLock("testref")
+	assert.NoError(t, err)
+	defer unlock("testref")
+
+	err = tryLock("testref")
+	require.NotNil(t, err)
+	assert.Contains(t, err.Error(), "ref testref locked for ")
+}