Pass NodeContext, ConnMan, BanMan references more places

So g_connman and g_banman globals can be removed next commit.

src/node/context.h

@@ -13,11 +13,26 @@ class Chain;
 class ChainClient;
 } // namespace interfaces
 
-//! Pointers to interfaces used during init and destroyed on shutdown.
+//! NodeContext struct containing references to chain state and connection
+//! state.
+//!
+//! This is used by init, rpc, and test code to pass object references around
+//! without needing to declare the same variables and parameters repeatedly, or
+//! to use globals. More variables could be added to this struct (particularly
+//! references to validation and mempool objects) to eliminate use of globals
+//! and make code more modular and testable. The struct isn't intended to have
+//! any member functions. It should just be a collection of references that can
+//! be used without pulling in unwanted dependencies or functionality.
 struct NodeContext
 {
     std::unique_ptr<interfaces::Chain> chain;
     std::vector<std::unique_ptr<interfaces::ChainClient>> chain_clients;
+
+    //! Declare default constructor and destructor that are not inline, so code
+    //! instantiating the NodeContext struct doesn't need to #include class
+    //! definitions for all the unique_ptr members.
+    NodeContext();
+    ~NodeContext();
 };
 
 #endif // BITCOIN_NODE_CONTEXT_H