message: Differentiate send/receive of headers/eom in QLog
  Summary:
  as title. Currently both send and receive of EOM read like send and
  both send and receive of Headers read like receive.
diff: @@ -74,7 +74,9 @@ constexpr auto kQLogTitleField = "title";
  constexpr auto kQLogDescriptionField = "description";
  constexpr auto kQLogTraceCountField = "trace_count";
  constexpr auto kEOM = "eom";
  +constexpr auto kOnEOM = "on eom";
  constexpr auto kStreamBlocked = "stream blocked";
  +constexpr auto kHeaders = "headers";
  constexpr auto kOnHeaders = "on headers";
  constexpr auto kOnError = "on error";
  constexpr auto kPushPromise = "push promise";
  