message: io_uring: mark callbacks as noexcept
  Summary: Rather than forcing the IoUringBackend to deal with exceptions - push it to the callbacks like other async callbacks (eg folly::AsyncTransport)
diff: @@ -482,7 +482,7 @@ class QuicServerWorker : public folly::AsyncUDPSocket::ReadCallback,
  }
  // from EventRecvmsgCallback
  - EventRecvmsgCallback::MsgHdr* allocateData() override {
  + EventRecvmsgCallback::MsgHdr* allocateData() noexcept override {
  auto* ret = msgHdr_.release();
  if (!ret) {
  ret = new MsgHdr(this);
  @@ -493,7 +493,8 @@ class QuicServerWorker : public folly::AsyncUDPSocket::ReadCallback,
  return ret;
  }
  - EventRecvmsgMultishotCallback::Hdr* allocateRecvmsgMultishotData() override {
  + EventRecvmsgMultishotCallback::Hdr* allocateRecvmsgMultishotData() noexcept
  + override {
  return new MultishotHdr(this);
  }
  