ilm: Remove object in HEAD/GET if having an applicable ILM rule (#11296)

Remove an object on the fly if there is a lifecycle rule with delete
expiry action for the corresponding object.

cmd/storage-datatypes.go

@@ -155,6 +155,9 @@ type FileInfo struct {
 	VersionPurgeStatus            VersionPurgeStatusType
 
 	Data []byte // optionally carries object data
+
+	NumVersions      int
+	SuccessorModTime time.Time
 }
 
 // VersionPurgeStatusKey denotes purge status in metadata