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

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

for (const uint256& hash : vtxid)
            a.push_back(hash.ToString());
        if (!include_mempool_sequence) {
            return a;
        } else {
            UniValue o(UniValue::VOBJ);
            o.pushKV("txids", a);
            o.pushKV("mempool_sequence", mempool_sequence);
            return o;
        }
    }
}
static RPCHelpMan getrawmempool()
{
    return RPCHelpMan{"getrawmempool",
                "\nReturns all transaction ids in memory pool as a json array of string transaction ids.\n"
                "\nHint: use getmempoolentry to fetch a specific transaction from the mempool.\n",
                {
                    {"verbose", RPCArg::Type::BOOL, RPCArg::Default{false}, "True for a json object, false for array of transaction ids"},
                    {"mempool_sequence", RPCArg::Type::BOOL, RPCArg::Default{false}, "If verbose=false, returns a json object with transaction list and mempool sequence number attached."},
                },
                {
                    RPCResult{"for verbose = false",
                        RPCResult::Type::ARR, "", "",
                        {
                            {RPCResult::Type::STR_HEX, "", "The transaction id"},
                        }},
                    RPCResult{"for verbose = true",
                        RPCResult::Type::OBJ_DYN, "", "",
                        {