implement a safer completeMultipart implementation (#20227)

- optimize writing part.N.meta by writing both part.N
  and its meta in sequence without network component.

- remove part.N.meta, part.N which were partially success
  ful, in quorum loss situations during renamePart()

- allow for strict read quorum check arbitrated via ETag
  for the given part number, this makes it double safer
  upon final commit.

- return an appropriate error when read quorum is missing,
  instead of returning InvalidPart{}, which is non-retryable
  error. This kind of situation can happen when many
  nodes are going offline in rotation, an example of such
  a restart() behavior is statefulset updates in k8s.

fixes #20091

internal/grid/handlers.go

@@ -113,6 +113,7 @@ const (
 	HandlerRenameDataInline
 	HandlerRenameData2
 	HandlerCheckParts2
+	HandlerRenamePart
 
 	// Add more above here ^^^
 	// If all handlers are used, the type of Handler can be changed.
@@ -194,6 +195,7 @@ var handlerPrefixes = [handlerLast]string{
 	HandlerRenameDataInline:            storagePrefix,
 	HandlerRenameData2:                 storagePrefix,
 	HandlerCheckParts2:                 storagePrefix,
+	HandlerRenamePart:                  storagePrefix,
 }
 
 const (