Move shim protos into linux pkg

This moves the shim's API and protos out of the containerd services
package and into the linux runtime package. This is because the shim is
an implementation detail of the linux runtime that we have and it is not
a containerd user facing api.

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

plugin/task.go

@@ -28,9 +28,9 @@ type Task interface {
 	// Processes returns all pids for the container
 	Processes(context.Context) ([]uint32, error)
 	// Pty resizes the processes pty/console
-	Pty(context.Context, uint32, ConsoleSize) error
+	ResizePty(context.Context, uint32, ConsoleSize) error
 	// CloseStdin closes the processes stdin
-	CloseStdin(context.Context, uint32) error
+	CloseIO(context.Context, uint32) error
 	// Checkpoint checkpoints a container to an image with live system data
 	Checkpoint(context.Context, string, map[string]string) error
 	// DeleteProcess deletes a specific exec process via the pid