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/go-macaron/session/file.go

@@ -81,6 +81,11 @@ func (s *FileStore) Release() error {
 	s.p.lock.Lock()
 	defer s.p.lock.Unlock()
 
+	// Skip encoding if the data is empty
+	if len(s.data) == 0 {
+		return nil
+	}
+
 	data, err := EncodeGob(s.data)
 	if err != nil {
 		return err