test: add int tests for failed & abandoned open

Add integration tests to verify channel open reset and
pruning handlers. Tests cover:
- channel_open_failed resetting state to allow retry.
- channel_open_failed error on invalid state.
- channel_open_abandoned pruning all open state.
- error handling for nonexistent channels.

Author: martinsaposnic

lightning-liquidity/tests/common/mod.rs

@@ -67,7 +67,7 @@ type LockingWrapper<T> = lightning::routing::scoring::MultiThreadedLockableScore
 #[cfg(not(c_bindings))]
 type LockingWrapper<T> = std::sync::Mutex<T>;
 
-type ChannelManager = channelmanager::ChannelManager<
+pub type ChannelManager = channelmanager::ChannelManager<
 	Arc<ChainMonitor>,
 	Arc<test_utils::TestBroadcaster>,
 	Arc<KeysManager>,