Add metrics type alias

This will help to decouple the import in CRI from the cgroups package
directly by importing the type alias in containerd repo.

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

metrics/types/v1/types.go

@@ -0,0 +1,44 @@
+// +build linux
+
+/*
+   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 v1
+
+import "github.com/containerd/cgroups"
+
+type (
+	// Metrics alias
+	Metrics = cgroups.Metrics
+	// BlkIOEntry alias
+	BlkIOEntry = cgroups.BlkIOEntry
+	// MemoryStat alias
+	MemoryStat = cgroups.MemoryStat
+	// CPUStat alias
+	CPUStat = cgroups.CPUStat
+	// CPUUsage alias
+	CPUUsage = cgroups.CPUUsage
+	// BlkIOStat alias
+	BlkIOStat = cgroups.BlkIOStat
+	// PidsStat alias
+	PidsStat = cgroups.PidsStat
+	// RdmaStat alias
+	RdmaStat = cgroups.RdmaStat
+	// RdmaEntry alias
+	RdmaEntry = cgroups.RdmaEntry
+	// HugetlbStat alias
+	HugetlbStat = cgroups.HugetlbStat
+)