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

cmd/storage-datatypes.go

@@ -494,6 +494,16 @@ type RenameFileHandlerParams struct {
 	DstFilePath string `msg:"dp"`
 }
 
+// RenamePartHandlerParams are parameters for RenamePartHandler.
+type RenamePartHandlerParams struct {
+	DiskID      string `msg:"id"`
+	SrcVolume   string `msg:"sv"`
+	SrcFilePath string `msg:"sp"`
+	DstVolume   string `msg:"dv"`
+	DstFilePath string `msg:"dp"`
+	Meta        []byte `msg:"m"`
+}
+
 // ReadAllHandlerParams are parameters for ReadAllHandler.
 type ReadAllHandlerParams struct {
 	DiskID   string `msg:"id"`
@@ -547,6 +557,16 @@ type ListDirResult struct {
 	Entries []string `msg:"e"`
 }
 
+// ReadPartsReq - send multiple part paths to read from
+type ReadPartsReq struct {
+	Paths []string `msg:"p"`
+}
+
+// ReadPartsResp - is the response for ReadPartsReq
+type ReadPartsResp struct {
+	Infos []*ObjectPartInfo `msg:"is"`
+}
+
 // DeleteBulkReq - send multiple paths in same delete request.
 type DeleteBulkReq struct {
 	Paths []string `msg:"p"`