Squashed commit of the following:

commit d8f03ec
Author: Dr. Denis Štogl <[email protected]>
Date:   Mon Dec 18 15:06:24 2023 +0100

    Fix tests.

commit 21c43a1
Author: Dr. Denis Štogl <[email protected]>
Date:   Mon Dec 18 14:53:25 2023 +0100

    Added functionality and tests for getting robot description from the topic.

commit ac71462
Author: Dr. Denis Štogl <[email protected]>
Date:   Mon Dec 18 12:33:20 2023 +0100

    Fixup the test URDF to not crash unneccessray the stack. This was hidden by catching all exceptions until now.

commit f975c23
Author: Dr. Denis Štogl <[email protected]>
Date:   Mon Dec 18 11:20:55 2023 +0100

    Remove support for description from parameter from the tests. Don't throw errors when comparing URDF and exported interfaces but add warning about this.

commit 6cf6ed5
Author: Dr. Denis Štogl <[email protected]>
Date:   Mon Dec 18 10:50:59 2023 +0100

    Make variable name clearer: rename 'request' to 'controller_name'.

commit ec3a1b4
Author: Dr. Denis Štogl <[email protected]>
Date:   Sun Dec 17 15:07:27 2023 +0100

    Optimize prepre/perform switch in CM and add additional documentation about it in the RM.

commit 1b26207
Author: Dr. Denis Štogl <[email protected]>
Date:   Tue Dec 12 11:08:51 2023 +0100

    Move 'manage_switch' method and 'do_switch' flag to more appropriate positions.

commit 6d5cc16
Author: Dr. Denis Štogl <[email protected]>
Date:   Tue Dec 12 11:07:17 2023 +0100

    Remove loading from robot description from parameter.

commit 361b92e
Author: Dr. Denis Štogl <[email protected]>
Date:   Tue Dec 12 11:17:20 2023 +0100

    Recover defintion of 'active_state' variable.

commit 9530927
Author: Dr. Denis <[email protected]>
Date:   Mon Dec 11 20:05:56 2023 +0100

    Update controller_manager.cpp

commit 03549ef
Author: Dr. Denis <[email protected]>
Date:   Mon Dec 11 18:19:16 2023 +0100

    Remove old parameter from tests.

commit efed392
Author: Dr. Denis <[email protected]>
Date:   Mon Dec 11 18:11:01 2023 +0100

    Remove deprecated parameters and warning about getting robot descritpion from parameter.

commit 0a6b107
Author: Dr. Denis Štogl <[email protected]>
Date:   Sun Dec 17 15:07:27 2023 +0100

    Optimize prepre/perform switch in RM and add additional documentation about it.

commit 44e3b72
Author: Dr. Denis Štogl <[email protected]>
Date:   Sun Dec 17 15:06:16 2023 +0100

    [RM] Separate tests for prepare and perform switch because they are long.

commit d033cf8
Author: Dr. Denis Štogl <[email protected]>
Date:   Sun Dec 17 19:49:24 2023 +0100

    Revert "Make reference interfaces of chainable controllers available in inactive state."

    This reverts commit 485b25f.

commit 485b25f
Author: Dr. Denis Štogl <[email protected]>
Date:   Wed Dec 13 16:41:50 2023 +0100

    Make reference interfaces of chainable controllers available in inactive state.

commit f9766e2
Author: Dr. Denis Štogl <[email protected]>
Date:   Tue Dec 12 18:49:15 2023 +0100

    Protect components from being called only in inactive and active states.

commit c575b4e
Author: Dr. Denis Štogl <[email protected]>
Date:   Tue Dec 12 17:39:03 2023 +0100

    Add additional checks for non existing and not available interfaces.

controller_manager/CMakeLists.txt

@@ -150,6 +150,7 @@ if(BUILD_TESTING)
   )
   target_link_libraries(test_controller_manager_urdf_passing
     controller_manager
+    test_controller
     ros2_control_test_assets::ros2_control_test_assets
   )
   ament_target_dependencies(test_controller_manager_urdf_passing

controller_manager/include/controller_manager/controller_manager.hpp

@@ -322,7 +322,7 @@ class ControllerManager : public rclcpp::Node
   std::vector<std::string> get_controller_names();
   std::pair<std::string, std::string> split_command_interface(
     const std::string & command_interface);
-  void subscribe_to_robot_description_topic();
+  void init_controller_manager();
 
   /**
    * Clear request lists used when switching controllers. The lists are shared between "callback"
@@ -536,6 +536,7 @@ class ControllerManager : public rclcpp::Node
 
   std::string robot_description_;
   rclcpp::Subscription<std_msgs::msg::String>::SharedPtr robot_description_subscription_;
+  rclcpp::TimerBase::SharedPtr robot_description_notification_timer_;
 
   struct SwitchParams
   {