Send a PASS IRC command if the “pass” config is sot by a user, on an IRC server

fix #3068

src/irc/irc_client.hpp

@@ -85,6 +85,7 @@ public:
    * Send the NICK irc command
    */
   void send_nick_command(const std::string& username);
+  void send_pass_command(const std::string& password);
   /**
    * Send the JOIN irc command.
    */