Consolidate gogo/protobuf dependencies under our own protobuf package

This would make gogo/protobuf migration easier.

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

pkg/process/deleted_state.go

@@ -26,7 +26,7 @@ import (
 
 	"github.com/containerd/console"
 	"github.com/containerd/containerd/errdefs"
-	google_protobuf "github.com/gogo/protobuf/types"
+	google_protobuf "github.com/containerd/containerd/protobuf/types"
 )
 
 type deletedState struct {