Merge pull request #48287 from thockin/json-iterator

Automatic merge from submit-queue

Use json-iterator instead of ugorji for JSON.

@smarterclayton @wojtek-t

Fixes #36120
xref #18762

```release-note
Switch JSON marshal/unmarshal to json-iterator library.  Performance should be close to previous with no generated code.
```

Kubernetes-commit: 6a845c67f097cd76f9d90ab3c9c5b5603c70afe4

vendor/github.com/json-iterator/go/jsoniter.go

@@ -0,0 +1,18 @@
+// Package jsoniter implements encoding and decoding of JSON as defined in
+// RFC 4627 and provides interfaces with identical syntax of standard lib encoding/json.
+// Converting from encoding/json to jsoniter is no more than replacing the package with jsoniter
+// and variable type declarations (if any).
+// jsoniter interfaces gives 100% compatibility with code using standard lib.
+//
+// "JSON and Go"
+// (https://golang.org/doc/articles/json_and_go.html)
+// gives a description of how Marshal/Unmarshal operate
+// between arbitrary or predefined json objects and bytes,
+// and it applies to jsoniter.Marshal/Unmarshal as well.
+//
+// Besides, jsoniter.Iterator provides a different set of interfaces
+// iterating given bytes/string/reader
+// and yielding parsed elements one by one.
+// This set of interfaces reads input as required and gives
+// better performance.
+package jsoniter