making RBF available in swaps for increasing fees of pending transactions in internal wallet

[massmux]

It would be nice that when sending a swap originating from internal wallet (Bitcoin onchain) we would raise fees via RBF. Actually we see that such transactions are sent with RBF=False. So if should be sent as RBF=True and there should be introduced a command fo raise the fees of a pending transaction belonging to a swap.

[jackstar12]

Currently, RBF is disabled explicitly so we can do 0-conf lockup transactions on liquid, but we can stop doing that for mainchain.

Relevant: https://gdk.readthedocs.io/en/latest/gdk-create-tx.html#fee-bump

[michael1011]

Yeah, let's enable RBF for mainchain and implement a wallet bumpfee command