Add liquid wallet support to Shopstr's wallet

[Shopstr-LiquidDev]

I'm opening this issue as the work on replacing Cashu wallet with Liquid Bitcoin wallet has begun. This issue strives to describe the expectations and track the progress, in the linked PR.

This is powered by lwk_wasm library from Blockstream.

The code is being worked on is located in feat/integrate-liquid-wallet branch.

Tasks

• Generate a watch-only wallet
• Allow importing of existing wallets by confidential descriptor
• Integrate lightning <-> liquid swaps using Boltz

[Shopstr-LiquidDev]

During the past 2 weeks I've implemented also the recovery mechanism for the wallet, added fiat api and also added embedded boltz.exchange swap into the app.