Remove windows code and simplify linux

Windows will not use containerd and its just unused code and unneed
complexity to keep it all around.

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

runtime/runtime.go

@@ -32,6 +32,27 @@ const (
 	InitProcessID  = "init"
 )
 
+type Checkpoint struct {
+	// Timestamp is the time that checkpoint happened
+	Created time.Time `json:"created"`
+	// Name is the name of the checkpoint
+	Name string `json:"name"`
+	// Tcp checkpoints open tcp connections
+	Tcp bool `json:"tcp"`
+	// UnixSockets persists unix sockets in the checkpoint
+	UnixSockets bool `json:"unixSockets"`
+	// Shell persists tty sessions in the checkpoint
+	Shell bool `json:"shell"`
+	// Exit exits the container after the checkpoint is finished
+	Exit bool `json:"exit"`
+}
+
+// PlatformProcessState container platform-specific fields in the ProcessState structure
+type PlatformProcessState struct {
+	Checkpoint string `json:"checkpoint"`
+	RootUID    int    `json:"rootUID"`
+	RootGID    int    `json:"rootGID"`
+}
 type State string
 
 type Resource struct {