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/xl-storage-format-v1.go

@@ -177,12 +177,15 @@ func (c *ChecksumInfo) UnmarshalJSON(data []byte) error {
 }
 
 // constant and shouldn't be changed.
-const legacyDataDir = "legacy"
+const (
+	legacyDataDir = "legacy"
+)
 
 func (m *xlMetaV1Object) ToFileInfo(volume, path string) (FileInfo, error) {
 	if !m.valid() {
 		return FileInfo{}, errFileCorrupt
 	}
+
 	fi := FileInfo{
 		Volume:    volume,
 		Name:      path,
@@ -194,9 +197,6 @@ func (m *xlMetaV1Object) ToFileInfo(volume, path string) (FileInfo, error) {
 		VersionID: m.VersionID,
 		DataDir:   m.DataDir,
 	}
-	if st, ok := m.Meta[ReservedMetadataPrefixLower+"transition-status"]; ok {
-		fi.TransitionStatus = st
-	}
 	return fi, nil
 }