fix: replication metadata comparsion and other fixes (#11410)

- using miniogo.ObjectInfo.UserMetadata is not correct
- using UserTags from Map->String() can change order
- ContentType comparison needs to be removed.
- Compare both lowercase and uppercase key names.
- do not silently error out constructing PutObjectOptions
  if tag parsing fails
- avoid notification for empty object info, failed operations
  should rely on valid objInfo for notification in all
  situations
- optimize copyObject implementation, also introduce a new 
  replication event
- clone ObjectInfo() before scheduling for replication
- add additional headers for comparison
- remove strings.EqualFold comparison avoid unexpected bugs
- fix pool based proxying with multiple pools
- compare only specific metadata

Co-authored-by: Poorna Krishnamoorthy <poornas@users.noreply.github.com>

cmd/xl-storage.go

@@ -386,7 +386,7 @@ func (s *xlStorage) CrawlAndGetDataUsage(ctx context.Context, cache dataUsageCac
 					oi:         oi,
 					bitRotScan: healOpts.Bitrot,
 				})
-				item.healReplication(ctx, objAPI, oi, &sizeS)
+				item.healReplication(ctx, objAPI, oi.Clone(), &sizeS)
 			}
 		}
 		sizeS.totalSize = totalSize