Check swap-in wallet at each block (#515)

The `WalletState` class contains absolute blockheights for utxos, and does not contain the current block height, so it is constant as soon as an utxo confirms. Even if `ElectrumMiniWallet` explicitly updated  `_walletStateFlow` (which it doesn't), it would be ignored because `MutableStateFlow` deduplicates events.

We need to look for swap-ins when either the wallet state or the current blockheight changes, otherwise we will only call `TrySwapIn` when the utxo reaches `weak` confirmation, and not when it graduates from `weak` to `deep` confirmation.

src/commonMain/kotlin/fr/acinq/lightning/io/Peer.kt

@@ -388,11 +388,10 @@ class Peer(
     }
 
     private suspend fun watchSwapInWallet() {
-        swapInWallet.walletStateFlow
-            .filter { it.consistent }
-            .collect {
-                val currentBlockHeight = currentTipFlow.filterNotNull().first().first
-                swapInCommands.send(SwapInCommand.TrySwapIn(currentBlockHeight, it, walletParams.swapInConfirmations, trustedSwapInTxs))
+        swapInWallet.walletStateFlow.combine(currentTipFlow.filterNotNull()) { walletState, currentTip -> currentTip.first to walletState }
+            .filter { (_, walletState) -> walletState.consistent }
+            .collect { (currentBlockHeight, walletState) ->
+                swapInCommands.send(SwapInCommand.TrySwapIn(currentBlockHeight, walletState, walletParams.swapInConfirmations, trustedSwapInTxs))
             }
     }