(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 (!EnsureWalletIsAvailable(fHelp))
        return NullUniValue;
    if (fHelp || params.size() != 0)
        throw runtime_error(
            "getwalletinfo\n"
            "Returns an object containing various wallet state info.\n"
            "\nResult:\n"
            "{\n"
            "  \"walletversion\": xxxxx,     (numeric) the wallet version\n"
            "  \"balance\": xxxxxxx,         (numeric) the total confirmed balance of the wallet in " + CURRENCY_UNIT + "\n"
            "  \"unconfirmed_balance\": xxx, (numeric) the total unconfirmed balance of the wallet in " + CURRENCY_UNIT + "\n"
            "  \"immature_balance\": xxxxxx, (numeric) the total immature balance of the wallet in " + CURRENCY_UNIT + "\n"
            "  \"txcount\": xxxxxxx,         (numeric) the total number of transactions in the wallet\n"
            "  \"keypoololdest\": xxxxxx,    (numeric) the timestamp (seconds since GMT epoch) of the oldest pre-generated key in the key pool\n"
            "  \"keypoolsize\": xxxx,        (numeric) how many new keys are pre-generated\n"
            "  \"unlocked_until\": ttt,      (numeric) the timestamp in seconds since epoch (midnight Jan 1 1970 GMT) that the wallet is unlocked for transfers, or 0 if the wallet is locked\n"
            "  \"paytxfee\": x.xxxx,         (numeric) the transaction fee configuration, set in " + CURRENCY_UNIT + "/kB\n"
            "}\n"
            "\nExamples:\n"
            + HelpExampleCli("getwalletinfo", "")
            + HelpExampleRpc("getwalletinfo", "")
        );