Merge pull request #65298 from nikhita/cherrypick-jsoniter-bump-1.9

Automatic merge from submit-queue.

Manual cherrypick of #65034 to 1.9: make json serializer case sensitive

fixes partially https://github.com/kubernetes/kubernetes/issues/64612

This PR imports the latest jsoniterator library so that case sensitivity during unmarshalling is optional. The PR also sets Kubernetes json serializer to be case sensitive.

**Release note**:

```release-note
ACTION REQUIRED: Kubernetes JSON deserializer is now case-sensitive to restore compatibility with pre-1.8 servers. If your config files contains fields with wrong case, the config files will be now invalid.
```

/sig api-machinery
/kind bug
/assign caesarxuchao liggitt thockin sttts mbohlool

Kubernetes-commit: f4cf484c2cb6056e28fb9759a3c913be3eed990a

vendor/github.com/modern-go/reflect2/safe_struct.go

@@ -0,0 +1,29 @@
+package reflect2
+
+type safeStructType struct {
+	safeType
+}
+
+func (type2 *safeStructType) FieldByName(name string) StructField {
+	field, found := type2.Type.FieldByName(name)
+	if !found {
+		panic("field " + name + " not found")
+	}
+	return &safeField{StructField: field}
+}
+
+func (type2 *safeStructType) Field(i int) StructField {
+	return &safeField{StructField: type2.Type.Field(i)}
+}
+
+func (type2 *safeStructType) FieldByIndex(index []int) StructField {
+	return &safeField{StructField: type2.Type.FieldByIndex(index)}
+}
+
+func (type2 *safeStructType) FieldByNameFunc(match func(string) bool) StructField {
+	field, found := type2.Type.FieldByNameFunc(match)
+	if !found {
+		panic("field match condition not found in " + type2.Type.String())
+	}
+	return &safeField{StructField: field}
+}