validate storage class across pools when setting config (#11320)

```
mc admin config set alias/ storage_class standard=EC:3
```

should only succeed if parity ratio is valid for all
server pools, if not we should fail proactively.

This PR also needs to bring other changes now that
we need to cater for variadic drive counts per pool.

Bonus fixes also various bugs reproduced with

- GetObjectWithPartNumber()
- CopyObjectPartWithOffsets()
- CopyObjectWithMetadata()
- PutObjectPart,PutObject with truncated streams

cmd/api-errors.go

@@ -87,6 +87,7 @@ const (
 	ErrInvalidMaxUploads
 	ErrInvalidMaxParts
 	ErrInvalidPartNumberMarker
+	ErrInvalidPartNumber
 	ErrInvalidRequestBody
 	ErrInvalidCopySource
 	ErrInvalidMetadataDirective
@@ -437,6 +438,11 @@ var errorCodes = errorCodeMap{
 		Description:    "Argument partNumberMarker must be an integer.",
 		HTTPStatusCode: http.StatusBadRequest,
 	},
+	ErrInvalidPartNumber: {
+		Code:           "InvalidPartNumber",
+		Description:    "The requested partnumber is not satisfiable",
+		HTTPStatusCode: http.StatusRequestedRangeNotSatisfiable,
+	},
 	ErrInvalidPolicyDocument: {
 		Code:           "InvalidPolicyDocument",
 		Description:    "The content of the form does not meet the conditions specified in the policy document.",