(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.
```

{
    CWalletDB walletdb(pwalletMain->strWalletFile);
    return GetAccountBalance(walletdb, strAccount, nMinDepth, filter);
}
UniValue getbalance(const UniValue& params, bool fHelp)
{
    if (!EnsureWalletIsAvailable(fHelp))
        return NullUniValue;
    if (fHelp || params.size() > 3)
        throw runtime_error(
            "getbalance ( \"account\" minconf includeWatchonly )\n"
            "\nIf account is not specified, returns the server's total available balance.\n"
            "If account is specified (DEPRECATED), returns the balance in the account.\n"
            "Note that the account \"\" is not the same as leaving the parameter out.\n"
            "The server total may be different to the balance in the default \"\" account.\n"
            "\nArguments:\n"
            "1. \"account\"      (string, optional) DEPRECATED. The selected account, or \"*\" for entire wallet. It may be the default account using \"\".\n"
            "2. minconf          (numeric, optional, default=1) Only include transactions confirmed at least this many times.\n"
            "3. includeWatchonly (bool, optional, default=false) Also include balance in watchonly addresses (see 'importaddress')\n"
            "\nResult:\n"
            "amount              (numeric) The total amount in " + CURRENCY_UNIT + " received for this account.\n"