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_vAddedNodes);
    for (const std::string& it : vAddedNodes) {
        if (strNode == it) return false;
    }
    vAddedNodes.push_back(strNode);
    return true;
}
bool CConnman::RemoveAddedNode(const std::string& strNode)
{
    LOCK(cs_vAddedNodes);
    for(std::vector<std::string>::iterator it = vAddedNodes.begin(); it != vAddedNodes.end(); ++it) {
        if (strNode == *it) {
            vAddedNodes.erase(it);
            return true;
        }
    }
    return false;
}
size_t CConnman::GetNodeCount(NumConnections flags)