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/hashicorp/go-hclog/stacktrace.go

@@ -40,12 +40,13 @@ var (
 	}
 )
 
-// A stacktrace gathered by a previous call to log.Stacktrace. If passed
-// to a logging function, the stacktrace will be appended.
+// CapturedStacktrace represents a stacktrace captured by a previous call
+// to log.Stacktrace. If passed to a logging function, the stacktrace
+// will be appended.
 type CapturedStacktrace string
 
-// Gather a stacktrace of the current goroutine and return it to be passed
-// to a logging function.
+// Stacktrace captures a stacktrace of the current goroutine and returns
+// it to be passed to a logging function.
 func Stacktrace() CapturedStacktrace {
 	return CapturedStacktrace(takeStacktrace())
 }