Bring acl test module into the test tree

src/node/tests/acl.rs was added by PR #50 but never declared in
src/node/tests/mod.rs, so none of its 4 unit tests ran. The tests
themselves still compile and pass against current master code —
the fix is a one-line mod declaration. Test count goes from 1031
to 1035.

No code under test changes. This only adds previously-dormant
coverage of the ACL enforcement call sites (outbound connect,
inbound msg1, outbound msg2).

src/node/tests/mod.rs

@@ -4,6 +4,7 @@ use crate::transport::{LinkDirection, TransportAddr, packet_channel};
 use crate::utils::index::SessionIndex;
 use std::time::Duration;
 
+mod acl;
 #[cfg(target_os = "linux")]
 mod ble;
 mod bloom;