Add screen to spend expired swap-ins

[dpad85]

This PR adds a new screen accessible from the swap-in wallet view that lets users spend cancelled funds that have expired and are not eligible to be swapped to Lightning anymore.

Previously, users needed to perform a manual procedure to spend cancelled funds.

@robbiehanson if you have suggestions for the wording in the new screens, do not hesitate.

This PR depends on https://github.com/ACINQ/lightning-kmp/tree/spend-expired-swapin (not merged yet).

Android screens

Tapping on Cancelled funds opens the screen to spend the cancelled funds.

The address and the feerate are set by the user.

The amount cannot be modified. It depends on what is available in the wallet.
See: peerManager.swapInWallet.readyForRefund.balance.

Low feerate check

Using a feerate below the mempool.space hour estimation triggers a "low feerate" warning, like for the splice-out screen (although unlike splice-outs, Phoenix cannot splice-CPFP that transaction later on, so the message is different and the acceleration part of it is removed).

[robbiehanson]

iOS screens so far:

This is in branch ios-564 which is rebased on master, and requires latest commit from lightning-kmp spend-expired-swapin.

[dpad85]

Cherry-picked ios-564 to include the iOS changes and merged master.

I also added support for ACINQ/lightning-kmp#657. This PR makes the peer's client and watcher interfaces (i.e., may not always be ElectrumClient/Watcher).

In theory it meansPeer.swapInWallet and Peer.finalWallet may be null, although in our case, they are always defined since Phoenix is always using Electrum. So I've added 2 extensions for Peer (see PeerManager): Peer.phoenixSwapInWallet and Peer.finalSwapInWallet. @robbiehanson if you used Peer.swapInWallet and Peer.finalWallet in the iOS app, you will have to switch and use these 2 extensions instead.