During rolling forward in `ReplayBlocks()` the UI progress starts with 0 then, once sync up again, jumps to 100%. This process can take pretty long and it would be good to show some progress steps within the RollingForwardBlock loop (`for (int nHeight = nForkHeight + 1; nHeight <= pindexNew->nHeight; ++nHeight) {`)
private:
    /**
     * The set of all CBlockIndex entries with BLOCK_VALID_TRANSACTIONS (for itself and all ancestors) and
     * as good as our current tip or better. Entries may be failed, though, and pruning nodes may be
     * missing the data for the block.
     */
    std::set<CBlockIndex*, CBlockIndexWorkComparator> setBlockIndexCandidates;
    /**
     * Every received block is assigned a unique and increasing identifier, so we
     * know which one to give priority in case of a fork.
     */
    CCriticalSection cs_nBlockSequenceId;
    
    int32_t nBlockSequenceId = 1;
    
    int32_t nBlockReverseSequenceId = -1;