net: Break disconnecting out of Ban()

These are separate events which need to be carried out by separate subsystems.

This also cleans up some whitespace and tabs in qt to avoid getting flagged by
the linter.

Current behavior is preserved.

src/net.h

@@ -282,6 +282,8 @@ public:
     size_t GetNodeCount(NumConnections num);
     void GetNodeStats(std::vector<CNodeStats>& vstats);
     bool DisconnectNode(const std::string& node);
+    bool DisconnectNode(const CSubNet& subnet);
+    bool DisconnectNode(const CNetAddr& addr);
     bool DisconnectNode(NodeId id);
 
     ServiceFlags GetLocalServices() const;