Rename QUIC keyset functions for clarification
Rename QUIC keyset functions for clarification

This commit renames functions related to QUIC keyset (st_quic_keyset_t)
to clarify they operate on QUIC keyset.

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