Add Get/Put Bucket Lock Configuration API support (#8120)

This feature implements [PUT Bucket object lock configuration][1] and
[GET Bucket object lock configuration][2]. After object lock
configuration is set, existing and new objects are set to WORM for
specified duration. Currently Governance mode works exactly like
Compliance mode.

Fixes #8101

[1] https://docs.aws.amazon.com/AmazonS3/latest/API/RESTBucketPUTObjectLockConfiguration.html
[2] https://docs.aws.amazon.com/AmazonS3/latest/API/RESTBucketGETObjectLockConfiguration.html

cmd/globals.go

@@ -202,6 +202,8 @@ var (
 	// Is worm enabled
 	globalWORMEnabled bool
 
+	globalBucketRetentionConfig = newBucketRetentionConfig()
+
 	// Disk cache drives
 	globalCacheConfig cache.Config