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/erasure-metadata.go

@@ -151,6 +151,8 @@ func (fi FileInfo) ToObjectInfo(bucket, object string) ObjectInfo {
 	}
 
 	objInfo.TransitionStatus = fi.TransitionStatus
+	objInfo.transitionedObjName = fi.TransitionedObjName
+	objInfo.TransitionTier = fi.TransitionTier
 
 	// etag/md5Sum has already been extracted. We need to
 	// remove to avoid it from appearing as part of
@@ -167,11 +169,15 @@ func (fi FileInfo) ToObjectInfo(bucket, object string) ObjectInfo {
 	} else {
 		objInfo.StorageClass = globalMinioDefaultStorageClass
 	}
+
 	objInfo.VersionPurgeStatus = fi.VersionPurgeStatus
 	// set restore status for transitioned object
-	if ongoing, exp, err := parseRestoreHeaderFromMeta(fi.Metadata); err == nil {
-		objInfo.RestoreOngoing = ongoing
-		objInfo.RestoreExpires = exp
+	restoreHdr, ok := fi.Metadata[xhttp.AmzRestore]
+	if ok {
+		if restoreStatus, err := parseRestoreObjStatus(restoreHdr); err == nil {
+			objInfo.RestoreOngoing = restoreStatus.Ongoing()
+			objInfo.RestoreExpires, _ = restoreStatus.Expiry()
+		}
 	}
 	// Success.
 	return objInfo