Add initial support for bucket lifecycle (#7563)

This PR is based off @sinhaashish's PR for object lifecycle
management, which includes support only for,
- Expiration of object
- Filter using object prefix (_not_ object tags)

N B the code for actual expiration of objects will be included in a
subsequent PR.

pkg/lifecycle/action.go

@@ -0,0 +1,33 @@
+/*
+ * MinIO Cloud Storage, (C) 2019 MinIO, Inc.
+ *
+ * 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 lifecycle
+
+// Action - policy action.
+// Refer https://docs.aws.amazon.com/IAM/latest/UserGuide/list_amazons3.html
+// for more information about available actions.
+type Action string
+
+const (
+	// PutBucketLifecycleAction - PutBucketLifecycle Rest API action.
+	PutBucketLifecycleAction = "s3:PutBucketLifecycle"
+
+	// GetBucketLifecycleAction - GetBucketLifecycle Rest API action.
+	GetBucketLifecycleAction = "s3:GetBucketLifecycle"
+
+	// DeleteBucketLifecycleAction - DeleteBucketLifecycleAction Rest API action.
+	DeleteBucketLifecycleAction = "s3:DeleteBucketLifecycle"
+)