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/github.com/coreos/go-oidc/.travis.yml

@@ -0,0 +1,16 @@
+language: go
+
+go:
+  - "1.12"
+  - "1.13"
+
+install:
+ - go get -v -t github.com/coreos/go-oidc/...
+ - go get golang.org/x/tools/cmd/cover
+ - go get golang.org/x/lint/golint
+
+script:
+ - ./test
+
+notifications:
+  email: false