add new fields for `%{http3.stats}x`
add new fields for `%{http3.stats}x`

devnexen/h2o,h2o/h2o,devnexen/h2o,h2o/h2o,cwyang/h2o,yannick/h2o,h2o/h2o,yannick/h2o,devnexen/h2o,cwyang/h2o,devnexen/h2o,devnexen/h2o,cwyang/h2o,h2o/h2o,cwyang/h2o,yannick/h2o,h2o/h2o,yannick/h2o,devnexen/h2o,h2o/h2o,devnexen/h2o,yannick/h2o,devnexen/h2o,h2o/h2o,yannick/h2o,cwyang/h2o,yannick/h2o,cwyang/h2o,h2o/h2o,cwyang/h2o,h2o/h2o,cwyang/h2o,yannick/h2o,yannick/h2o,devnexen/h2o