feat: add multiple authentication methods, token and oidc.

token is the current token comparison, and oidc generates oidc token using client-credentials flow. in addition - add ping verification using the same method

vendor/golang.org/x/oauth2/README.md

@@ -0,0 +1,36 @@
+# OAuth2 for Go
+
+[![Build Status](https://travis-ci.org/golang/oauth2.svg?branch=master)](https://travis-ci.org/golang/oauth2)
+[![GoDoc](https://godoc.org/golang.org/x/oauth2?status.svg)](https://godoc.org/golang.org/x/oauth2)
+
+oauth2 package contains a client implementation for OAuth 2.0 spec.
+
+## Installation
+
+~~~~
+go get golang.org/x/oauth2
+~~~~
+
+Or you can manually git clone the repository to
+`$(go env GOPATH)/src/golang.org/x/oauth2`.
+
+See godoc for further documentation and examples.
+
+* [godoc.org/golang.org/x/oauth2](https://godoc.org/golang.org/x/oauth2)
+* [godoc.org/golang.org/x/oauth2/google](https://godoc.org/golang.org/x/oauth2/google)
+
+## Policy for new packages
+
+We no longer accept new provider-specific packages in this repo if all
+they do is add a single endpoint variable. If you just want to add a
+single endpoint, add it to the
+[godoc.org/golang.org/x/oauth2/endpoints](https://godoc.org/golang.org/x/oauth2/endpoints)
+package.
+
+## Report Issues / Send Patches
+
+This repository uses Gerrit for code changes. To learn how to submit changes to
+this repository, see https://golang.org/doc/contribute.html.
+
+The main issue tracker for the oauth2 repository is located at
+https://github.com/golang/oauth2/issues.