message: Use F14FastSet for opened stream group
  Summary: As in title. Doesn't need to be sorted or individually allocated.
diff: #include <quic/state/StreamData.h>
  #include <quic/state/TransportSettings.h>
  #include <numeric>
  -#include <set>
  namespace quic {
  namespace detail {
  @@ -858,7 +857,7 @@ class QuicStreamManager {
  * Consume the new peer stream groups using the parameter vector.
  */
  auto consumeNewPeerStreamGroups() {
  - std::set<StreamGroupId> result;
  + decltype(newPeerStreamGroups_) result;
  result.swap(newPeerStreamGroups_);
  return result;
  }
  @@ -1114,7 +1113,7 @@ class QuicStreamManager {
  std::vector<StreamId> newGroupedPeerStreams_;
  // Recently opened peer stream groups.
  - std::set<StreamGroupId> newPeerStreamGroups_;
  + folly::F14FastSet<StreamGroupId> newPeerStreamGroups_;
  // Peer group ids seen.
  folly::F14FastSet<StreamGroupId> peerStreamGroupsSeen_;
  