(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.
```

list<COutputEntry> listReceived;
            list<COutputEntry> listSent;
            wtx.GetAmounts(listReceived, listSent, allFee, strSentAccount, filter);
            if (wtx.GetDepthInMainChain() >= nMinDepth)
            {
                BOOST_FOREACH(const COutputEntry& r, listReceived)
                    nBalance += r.amount;
            }
            BOOST_FOREACH(const COutputEntry& s, listSent)
                nBalance -= s.amount;
            nBalance -= allFee;
        }
        return  ValueFromAmount(nBalance);
    }
    string strAccount = AccountFromValue(params[0]);
    CAmount nBalance = GetAccountBalance(strAccount, nMinDepth, filter);
    return ValueFromAmount(nBalance);
}
UniValue getunconfirmedbalance(const UniValue &params, bool fHelp)
{
    if (!EnsureWalletIsAvailable(fHelp))
        return NullUniValue;
    if (fHelp || params.size() > 0)
        throw runtime_error(
                "getunconfirmedbalance\n"
                "Returns the server's total unconfirmed balance\n");
    LOCK2(cs_main, pwalletMain->cs_wallet);
    return ValueFromAmount(pwalletMain->GetUnconfirmedBalance());
}
UniValue movecmd(const UniValue& params, bool fHelp)