For every peer expose through `getpeerinfo` RPC whether or not we selected them as HB peers, and whether or not they selected us as HB peers.

Suggestion by @gmaxwell.
{
    LOCK(cs_vNodes);
    if (flags == CConnman::CONNECTIONS_ALL) 
        return vNodes.size();
    int nNum = 0;
    for (const auto& pnode : vNodes) {
        if (flags & (pnode->IsInboundConn() ? CONNECTIONS_IN : CONNECTIONS_OUT)) {
            nNum++;
        }
    }
    return nNum;
}
void CConnman::GetNodeStats(std::vector<CNodeStats>& vstats)
{
    vstats.clear();
    LOCK(cs_vNodes);
    vstats.reserve(vNodes.size());
    for (CNode* pnode : vNodes) {
        vstats.emplace_back();
        pnode->copyStats(vstats.back(), addrman.m_asmap);
    }
}
bool CConnman::DisconnectNode(const std::string& strNode)