lnworker: split dont_settle_htlcs

Splits `LNWallet.dont_settle_htlcs` into `LNWallet.dont_settle_htlcs`
and `LNWallet.dont_expire_htlcs`.

Registering a payment hash in dont_settle_htlcs will prevent it from
getting fulfilled if we have the preimage stored. The preimage will not
be released before the the payment hash gets removed from
dont_settle_htlcs. Htlcs can still get expired as usual or failed if no
preimage is known.
This is only used by Just-in-time channel openings.

Registering a payment hash in dont_expire_htlcs allows to overwrite the
minimum final cltv delta value after which htlcs would usually get
expired. This allows to delay expiry of htlcs or, if the value in the
dont_settle_htlcs dict is None, completely prevent expiry and let the
htlc get expired onchain.

Splitting this up in two different dicts makes it more explicit and
easier to reason about what they are actually doing.

 Please enter the commit message for your changes. Lines starting

tests/test_commands.py

@@ -510,7 +510,7 @@ class TestCommandsTestnet(ElectrumTestCase):
         invoice = lndecode(invoice=result['invoice'])
         assert invoice.paymenthash.hex() == payment_hash
         assert payment_hash in wallet.lnworker.payment_info
-        assert payment_hash in wallet.lnworker.dont_settle_htlcs
+        assert payment_hash in wallet.lnworker.dont_expire_htlcs
         assert invoice.get_amount_sat() == 10000
         assert invoice.get_description() == "test"
         assert wallet.get_label_for_rhash(rhash=invoice.paymenthash.hex()) == "test"
@@ -521,7 +521,7 @@ class TestCommandsTestnet(ElectrumTestCase):
             wallet=wallet,
         )
         assert payment_hash not in wallet.lnworker.payment_info
-        assert payment_hash not in wallet.lnworker.dont_settle_htlcs
+        assert payment_hash not in wallet.lnworker.dont_expire_htlcs
         assert wallet.get_label_for_rhash(rhash=invoice.paymenthash.hex()) == ""
         assert cancel_result['cancelled'] == payment_hash
 
@@ -571,7 +571,6 @@ class TestCommandsTestnet(ElectrumTestCase):
             )
         assert settle_result['settled'] == payment_hash
         assert wallet.lnworker._preimages[payment_hash] == preimage.hex()
-        assert payment_hash not in wallet.lnworker.dont_settle_htlcs
         with (mock.patch.object(
             wallet.lnworker,
             'get_payment_value',

tests/test_lnpeer.py

@@ -218,6 +218,7 @@ class MockLNWallet(Logger, EventListener, NetworkRetryManager[LNPeerAddr]):
         self._preimages = {}
         self.stopping_soon = False
         self.downstream_to_upstream_htlc = {}
+        self.dont_expire_htlcs = {}
         self.dont_settle_htlcs = {}
         self.hold_invoice_callbacks = {}
         self._payment_bundles_pkey_to_canon = {}       # type: Dict[bytes, bytes]