(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 (walletdb.ReadBestBlock(locator))
            pindexRescan = FindForkInGlobalIndex(chainActive, locator);
        else
            pindexRescan = chainActive.Genesis();
    }
    if (chainActive.Tip() && chainActive.Tip() != pindexRescan)
    {
        
        
        
        if (fPruneMode)
        {
            CBlockIndex *block = chainActive.Tip();
            while (block && block->pprev && (block->pprev->nStatus & BLOCK_HAVE_DATA) && block->pprev->nTx > 0 && pindexRescan != block)
                block = block->pprev;
            if (pindexRescan != block)
                return InitError(_("Prune: last wallet synchronisation goes beyond pruned data. You need to -reindex (download the whole blockchain again in case of pruned node)"));
        }
        uiInterface.InitMessage(_("Rescanning..."));
        LogPrintf("Rescanning last %i blocks (from block %i)...\n", chainActive.Height() - pindexRescan->nHeight, pindexRescan->nHeight);
        nStart = GetTimeMillis();
        walletInstance->ScanForWalletTransactions(pindexRescan, true);
        LogPrintf(" rescan      %15dms\n", GetTimeMillis() - nStart);
        walletInstance->SetBestChain(chainActive.GetLocator());
        nWalletDBUpdated++;
        
        if (GetBoolArg("-zapwallettxes", false) && GetArg("-zapwallettxes", "1") != "2")
        {
            CWalletDB walletdb(walletFile);
            BOOST_FOREACH(const CWalletTx& wtxOld, vWtx)