Implement LND ExternalNode via gRPC with Mutex interior mutability

- Implement ExternalNode trait using lnd_grpc_rust with Mutex<LndClient>
- Log errors from spawned close_channel/force_close_channel streams

Author: febyeji

Cargo.toml

@@ -103,7 +103,7 @@ corepc-node = { version = "0.10.0", default-features = false, features = ["27_2"
 clightningrpc = { version = "0.3.0-beta.8", default-features = false }
 
 [target.'cfg(lnd_test)'.dev-dependencies]
-lnd_grpc_rust = { version = "2.10.0", default-features = false }
+lnd_grpc_rust = { version = "2.14.0", default-features = false }
 tokio = { version = "1.37", features = ["fs"] }
 
 [build-dependencies]