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.
const CService address;
    
    const CBlockIndex *pindexBestKnownBlock;
    
    uint256 hashLastUnknownBlock;
    
    const CBlockIndex *pindexLastCommonBlock;
    
    const CBlockIndex *pindexBestHeaderSent;
    
    int nUnconnectingHeaders;
    
    bool fSyncStarted;
    
    int64_t nHeadersSyncTimeout;
    
    int64_t nStallingSince;
    std::list<QueuedBlock> vBlocksInFlight;
    
    int64_t nDownloadingSince;
    int nBlocksInFlight;
    int nBlocksInFlightValidHeaders;
    
    bool fPreferredDownload;
    
    bool fPreferHeaders;
    
    bool fPreferHeaderAndIDs;
    /**