- Separation between SwapManager and its transport:
Legacy transpport uses http, Nostr uses websockets
- The transport uses a context to open/close connections.
This context is not async, because it needs to be called
from the GUI
- Swapserver fees values are initialized to None instead
of 0, so that any attempt to use them before the swap
manager is initialized will raise an exception.
- Remove swapserver fees disk caching (swap_pairs file)
- Regtests use http transport
- Android uses http transport (until QML is ready)
