feature: Fidelity Bonds

[rajarshimaitra]

In order to provide DOS resistance by malicious Makers, makers need to publish valid fidelity bonds. Takers can ban fidelity bonds of misbehaving makers.

The fidelity bond code exists here https://github.com/utxo-teleport/teleport-transactions/blob/master/src/wallet/fidelity.rs.

The tasks are following:

• This code needs to be modernized and polished.
• Makers should publish fidelity bonds onchain and include fidelity info in their offer details.
• Takers should ban fidelity bonds of malicious makers and not swap with them after missbehaving.