(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 (fHelp || params.size() > 0)
        throw runtime_error(
            "listlockunspent\n"
            "\nReturns list of temporarily unspendable outputs.\n"
            "See the lockunspent call to lock and unlock transactions for spending.\n"
            "\nResult:\n"
            "[\n"
            "  {\n"
            "    \"txid\" : \"transactionid\",     (string) The transaction id locked\n"
            "    \"vout\" : n                      (numeric) The vout value\n"
            "  }\n"
            "  ,...\n"
            "]\n"
            "\nExamples:\n"
            "\nList the unspent transactions\n"
            + HelpExampleCli("listunspent", "") +
            "\nLock an unspent transaction\n"
            + HelpExampleCli("lockunspent", "false \"[{\\\"txid\\\":\\\"a08e6907dbbd3d809776dbfc5d82e371b764ed838b5655e72f463568df1aadf0\\\",\\\"vout\\\":1}]\"") +
            "\nList the locked transactions\n"
            + HelpExampleCli("listlockunspent", "") +
            "\nUnlock the transaction again\n"
            + HelpExampleCli("lockunspent", "true \"[{\\\"txid\\\":\\\"a08e6907dbbd3d809776dbfc5d82e371b764ed838b5655e72f463568df1aadf0\\\",\\\"vout\\\":1}]\"") +
            "\nAs a json rpc call\n"
            + HelpExampleRpc("listlockunspent", "")
        );
    LOCK2(cs_main, pwalletMain->cs_wallet);
    vector<COutPoint> vOutpts;
    pwalletMain->ListLockedCoins(vOutpts);
    UniValue ret(UniValue::VARR);
    BOOST_FOREACH(COutPoint &outpt, vOutpts) {