(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.
```

{
    LOCK(cs_wallet);
    std::map<uint256, CWalletTx>::const_iterator it = mapWallet.find(hash);
    if (it == mapWallet.end())
        return NULL;
    return &(it->second);
}
CPubKey CWallet::GenerateNewKey()
{
    AssertLockHeld(cs_wallet); 
    bool fCompressed = CanSupportFeature(FEATURE_COMPRPUBKEY); 
    CKey secret;
    secret.MakeNewKey(fCompressed);
    
    if (fCompressed)
        SetMinVersion(FEATURE_COMPRPUBKEY);
    CPubKey pubkey = secret.GetPubKey();
    assert(secret.VerifyPubKey(pubkey));
    
    int64_t nCreationTime = GetTime();
    mapKeyMetadata[pubkey.GetID()] = CKeyMetadata(nCreationTime);
    if (!nTimeFirstKey || nCreationTime < nTimeFirstKey)
        nTimeFirstKey = nCreationTime;
    if (!AddKeyPubKey(secret, pubkey))
        throw std::runtime_error("CWallet::GenerateNewKey(): AddKey failed");
    return pubkey;
}
bool CWallet::AddKeyPubKey(const CKey& secret, const CPubKey &pubkey)