RPCs that return detailed information about mempool entries (e.g. `getmempoolentry` and `getrawmempool(verbose=True)` include the fields `fee`, `modifiedfee`, `descendantfees`, and `ancestorfees` which were marked as "DEPRECATED" and replaced with a `fees` object field in #12240 (since v0.17).

We should remove these fields, but first, properly deprecate them using `-deprecatedrpc`.

#### Useful skills:

- basic understanding of Bitcoin Core RPC interface

#### Want to work on this issue?

For guidance on contributing, please read [CONTRIBUTING.md](https://github.com/bitcoin/bitcoin/blob/master/CONTRIBUTING.md) before opening your pull request.

count = 0;
    while (cursor->Valid()) {
        COutPoint key;
        Coin coin;
        if (!cursor->GetKey(key) || !cursor->GetValue(coin)) return false;
        if (++count % 8192 == 0) {
            interruption_point();
            if (should_abort) {
                
                return false;
            }
        }
        if (count % 256 == 0) {
            
            uint32_t high = 0x100 * *key.hash.begin() + *(key.hash.begin() + 1);
            scan_progress = (int)(high * 100.0 / 65536.0 + 0.5);
        }
        if (needles.count(coin.out.scriptPubKey)) {
            out_results.emplace(key, coin);
        }
        cursor->Next();
    }
    scan_progress = 100;
    return true;
}
} 
static std::atomic<int> g_scan_progress;
static std::atomic<bool> g_scan_in_progress;
static std::atomic<bool> g_should_abort_scan;
class CoinsViewScanReserver