Show options if we do not have the liquidity to pay a lightning invoice:

pay onchain, open channel, rebalance.

If we do a swap or open a channel, the payment will be scheduled.

electrum/tests/test_lnpeer.py

@@ -158,6 +158,9 @@ class MockLNWallet(Logger, NetworkRetryManager[LNPeerAddr]):
 
         self.logger.info(f"created LNWallet[{name}] with nodeID={local_keypair.pubkey.hex()}")
 
+    def pay_scheduled_invoices(self):
+        pass
+
     def get_invoice_status(self, key):
         pass