Allow swapping inscriptions using the offers command

[casey]

Current, ord wallet offer create and ord wallet offer accept only allow swapping bitcoin for an inscription.

It would be nice, similar to @lifofifoX's SWAP, to make it possible to swap one inscription for another.

Something like:

ord wallet offer create --inscription ID0 --for ID1  --fee-rate 1
ord wallet offer accept --inscription ID0 --for ID1

--for is not a great name for the flag. We currently have --amount, which is the bitcoin amount, but if we're making this more generic over types of payment, we could consider changing that to.

Maybe --price, which accepts a bitcoin amount or inscription ID?