Support for remote tier management (#12090)

With this change, MinIO's ILM supports transitioning objects to a remote tier.
This change includes support for Azure Blob Storage, AWS S3 compatible object
storage incl. MinIO and Google Cloud Storage as remote tier storage backends.

Some new additions include:

 - Admin APIs remote tier configuration management

 - Simple journal to track remote objects to be 'collected'
   This is used by object API handlers which 'mutate' object versions by
   overwriting/replacing content (Put/CopyObject) or removing the version
   itself (e.g DeleteObjectVersion).

 - Rework of previous ILM transition to fit the new model
   In the new model, a storage class (a.k.a remote tier) is defined by the
   'remote' object storage type (one of s3, azure, GCS), bucket name and a
   prefix.

* Fixed bugs, review comments, and more unit-tests

- Leverage inline small object feature
- Migrate legacy objects to the latest object format before transitioning
- Fix restore to particular version if specified
- Extend SharedDataDirCount to handle transitioned and restored objects
- Restore-object should accept version-id for version-suspended bucket (#12091)
- Check if remote tier creds have sufficient permissions
- Bonus minor fixes to existing error messages

Co-authored-by: Poorna Krishnamoorthy <poorna@minio.io>
Co-authored-by: Krishna Srinivas <krishna@minio.io>
Signed-off-by: Harshavardhana <harsha@minio.io>

cmd/server-main.go

@@ -243,6 +243,9 @@ func newAllSubsystems() {
 
 	// Create new bucket replication subsytem
 	globalBucketTargetSys = NewBucketTargetSys()
+
+	// Create new ILM tier configuration subsystem
+	globalTierConfigMgr = NewTierConfigMgr()
 }
 
 func configRetriableErrors(err error) bool {
@@ -401,6 +404,13 @@ func initAllSubsystems(ctx context.Context, newObject ObjectLayer) (err error) {
 	// Initialize bucket targets sub-system.
 	globalBucketTargetSys.Init(ctx, buckets, newObject)
 
+	if globalIsErasure {
+		// Initialize transition tier configuration manager
+		err = globalTierConfigMgr.Init(ctx, newObject)
+		if err != nil {
+			return err
+		}
+	}
 	return nil
 }
 
@@ -510,7 +520,6 @@ func serverMain(ctx *cli.Context) {
 	if err != nil {
 		logFatalErrs(err, Endpoint{}, true)
 	}
-
 	logger.SetDeploymentID(globalDeploymentID)
 
 	// Enable background operations for erasure coding
@@ -538,7 +547,12 @@ func serverMain(ctx *cli.Context) {
 
 	if globalIsErasure { // to be done after config init
 		initBackgroundReplication(GlobalContext, newObject)
+		globalTierJournal, err = initTierDeletionJournal(GlobalContext.Done())
+		if err != nil {
+			logger.FatalIf(err, "Unable to initialize remote tier pending deletes journal")
+		}
 	}
+
 	if globalCacheConfig.Enabled {
 		// initialize the new disk cache objects.
 		var cacheAPI CacheObjectLayer