(from discussion on IRC. Currently a global `settxfee` has to be changed to override the fee rate, it would make sense to be able to specify it on a per-transaction basis. This would continue #7518)

```
-*- jonasschnelli thinks we should probably add a optional feerate parameter to fundrawtransaction
<wumpus> jonasschnelli: there isn't one yet?
-*- jonasschnelli looking..
<wumpus> I'm surprised, would be so much better than changing a global
<jonasschnelli> no.. i don't think so. Maybe there is a PR.
<sipa> there is a pr
<jonasschnelli> Hard to keep track of everything. :)
<wumpus> no, the PR does it wrong
```

Regarding implementation:

```
<jonasschnelli> The ugly thing is, that CreateTransaction uses the static DEFAULT_TARGET
<wumpus> passing in an optional feerate would be the obvious thing to do
<jonasschnelli> So, this would require some refactoring.
<sipa> just add a confirmation target to coincontrol
<jonasschnelli> Yes. This sounds good.
<wumpus> right, just slap it into coincontrol
<sipa> wasn't there a PR that added a bunch of options to fundrawtransaction?
<sipa> including that
<jonasschnelli> Not the feerate.
<jonasschnelli> But the rest is merged.
```

if (IsMine(*pwalletMain, entry.first) & includeWatchonly) 
            mapAccountBalances[entry.second.name] = 0;
    }
    for (map<uint256, CWalletTx>::iterator it = pwalletMain->mapWallet.begin(); it != pwalletMain->mapWallet.end(); ++it)
    {
        const CWalletTx& wtx = (*it).second;
        CAmount nFee;
        string strSentAccount;
        list<COutputEntry> listReceived;
        list<COutputEntry> listSent;
        int nDepth = wtx.GetDepthInMainChain();
        if (wtx.GetBlocksToMaturity() > 0 || nDepth < 0)
            continue;
        wtx.GetAmounts(listReceived, listSent, nFee, strSentAccount, includeWatchonly);
        mapAccountBalances[strSentAccount] -= nFee;
        BOOST_FOREACH(const COutputEntry& s, listSent)
            mapAccountBalances[strSentAccount] -= s.amount;
        if (nDepth >= nMinDepth)
        {
            BOOST_FOREACH(const COutputEntry& r, listReceived)
                if (pwalletMain->mapAddressBook.count(r.destination))
                    mapAccountBalances[pwalletMain->mapAddressBook[r.destination].name] += r.amount;
                else
                    mapAccountBalances[""] += r.amount;
        }
    }
    const list<CAccountingEntry> & acentries = pwalletMain->laccentries;
    BOOST_FOREACH(const CAccountingEntry& entry, acentries)
        mapAccountBalances[entry.strAccount] += entry.nCreditDebit;