While the user trying to fetch an invoice by specifing the quantity we do
not work as expected.
Running the command
```
lightning-cli fetchinvoice -k offer='lno1qgsqvgnwgcg35z6ee2h3yczraddm72xrfua9uve2rlrm9deu7xyfzrcgqffqszsk2p6hycmgv9ek2grpyphxjcm9ypmkjer8v46pyzmhd9jxwet5wvhxxmmdzsqs593pq0ylsvakdua5h976f4g3eautgjt3udvtyga47eaw7339sjrhpwpwz' quantity=2
```
and we answer back with
```json
{
"code": -32602,
"message": "quantity parameter required"
}
```
This is caused because we forget to bind the `quanity` field from the
RPC into the `invrequest`.
Reported-by: @aaronbarnardsound
Link: https://github.com/ElementsProject/lightning/issues/6089
Signed-off-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
Changelog-EXPERIMENTAL: fetchinvoice: fix: do not ignore the `quantity` field
into the invreq field.
Vincenzo Palazzo
fca62113f5