replace dep with go modules (#16017)

- guide shamelessly stolen from prometheus/prometheus
- updates local interface of oauth exchange
- updates local impl of hclogger
- bump jaeger client version

closes #16088

vendor/github.com/prometheus/procfs/README.md

@@ -0,0 +1,11 @@
+# procfs
+
+This procfs package provides functions to retrieve system, kernel and process
+metrics from the pseudo-filesystem proc.
+
+*WARNING*: This package is a work in progress. Its API may still break in
+backwards-incompatible ways without warnings. Use it at your own risk.
+
+[![GoDoc](https://godoc.org/github.com/prometheus/procfs?status.png)](https://godoc.org/github.com/prometheus/procfs)
+[![Build Status](https://travis-ci.org/prometheus/procfs.svg?branch=master)](https://travis-ci.org/prometheus/procfs)
+[![Go Report Card](https://goreportcard.com/badge/github.com/prometheus/procfs)](https://goreportcard.com/report/github.com/prometheus/procfs)