Move plugin type definitions to containerd plugins package

The plugins packages defines the plugins used by containerd.
Move all the types and properties to this package.

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

services/tasks/local.go

@@ -41,6 +41,7 @@ import (
 	"github.com/containerd/containerd/pkg/rdt"
 	"github.com/containerd/containerd/pkg/timeout"
 	"github.com/containerd/containerd/plugin"
+	"github.com/containerd/containerd/plugins"
 	"github.com/containerd/containerd/protobuf"
 	"github.com/containerd/containerd/protobuf/proto"
 	ptypes "github.com/containerd/containerd/protobuf/types"
@@ -75,7 +76,7 @@ type Config struct {
 
 func init() {
 	plugin.Register(&plugin.Registration{
-		Type:     plugin.ServicePlugin,
+		Type:     plugins.ServicePlugin,
 		ID:       services.TasksService,
 		Requires: tasksServiceRequires,
 		Config:   &Config{},
@@ -88,22 +89,22 @@ func init() {
 func initFunc(ic *plugin.InitContext) (interface{}, error) {
 	config := ic.Config.(*Config)
 
-	v2r, err := ic.GetByID(plugin.RuntimePluginV2, "task")
+	v2r, err := ic.GetByID(plugins.RuntimePluginV2, "task")
 	if err != nil {
 		return nil, err
 	}
 
-	m, err := ic.Get(plugin.MetadataPlugin)
+	m, err := ic.Get(plugins.MetadataPlugin)
 	if err != nil {
 		return nil, err
 	}
 
-	ep, err := ic.Get(plugin.EventPlugin)
+	ep, err := ic.Get(plugins.EventPlugin)
 	if err != nil {
 		return nil, err
 	}
 
-	monitor, err := ic.Get(plugin.TaskMonitorPlugin)
+	monitor, err := ic.Get(plugins.TaskMonitorPlugin)
 	if err != nil {
 		if !errdefs.IsNotFound(err) {
 			return nil, err