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/json-iterator/go/Gopkg.toml

@@ -0,0 +1,26 @@
+# Gopkg.toml example
+#
+# Refer to https://github.com/golang/dep/blob/master/docs/Gopkg.toml.md
+# for detailed Gopkg.toml documentation.
+#
+# required = ["github.com/user/thing/cmd/thing"]
+# ignored = ["github.com/user/project/pkgX", "bitbucket.org/user/project/pkgA/pkgY"]
+#
+# [[constraint]]
+#   name = "github.com/user/project"
+#   version = "1.0.0"
+#
+# [[constraint]]
+#   name = "github.com/user/project2"
+#   branch = "dev"
+#   source = "github.com/myfork/project2"
+#
+# [[override]]
+#  name = "github.com/x/y"
+#  version = "2.4.0"
+
+ignored = ["github.com/davecgh/go-spew*","github.com/google/gofuzz*","github.com/stretchr/testify*"]
+
+[[constraint]]
+  name = "github.com/modern-go/reflect2"
+  version = "1.0.0"