One-way Atomic Swap integration

[layters]

Details

This will allow users of more easily accessible cryptocurrencies (e.g BTC, ETH, LTC, etc.) to convert their cryptocurrency of choice to XMR. There will come a time when Monero is delisted from all centralized exchanges, making it difficult for the average person to acquire some XMR which is the reason why I am proposing this feature.

With this addition, multiple cryptocurrencies will be supported by neroshop indirectly while XMR remains the primary cryptocurrency used for sales and purchases.

References

https://github.com/noot/atomic-swap
https://github.com/comit-network/xmr-btc-swap
https://github.com/UnstoppableSwap/unstoppableswap-gui