Support different logging levels in ROS 2

[matthias-mayr]

When using the logger with different logging levels it crashes. Line reference:
https://github.com/RVMI/skiros2/blob/ed5bc907f8509f8223bf5c75ff2b7bcf9ff056e7/skiros2_common/skiros2_common/tools/logger.py#L180-L181

Stack trace when crashing:

Fiile "/opt/ros/humble/local/lib/python3.10/dist-packages/rclpy/impl/rcutils_logger.py", line 299, in log
    raise ValueError('Logger severity cannot be changed between calls.')
  File "/home/matthias/Workspaces/skiros2_ws/build/skiros2_common/skiros2_common/tools/logger.py", line 181, in log
    self.__log.log(self.msgToString(self.__LOG[-1]), logToLoggingMode[mode])
  File "/home/matthias/Workspaces/skiros2_ws/build/skiros2_common/skiros2_common/tools/logger.py", line 91, in logWarn
    def logWarn(self, msg, desc=None):     self.log(logMode.WARN, msg, desc)
  File "/home/matthias/Workspaces/skiros2_ws/build/skiros2_world_model/skiros2_world_model/ros/ontology_interface.py", line 32, in __init__
    log.warn("[{}]".format(self.__class__.__name__), "Service {} not available, waiting again ...".format(s.srv_name))
  File "/home/matthias/Workspaces/skiros2_ws/build/skiros2_world_model/skiros2_world_model/ros/world_model_interface.py", line 30, in __init__
    OntologyInterface.__init__(self, node, author_name, allow_spinning)
  File "/home/matthias/Workspaces/skiros2_ws/build/skiros2_skill/skiros2_skill/ros/skill_manager.py", line 188, in __init__
    self._wmi = wmi.WorldModelInterface(node, agent_name, make_cache=True, allow_spinning=True)
  File "/home/matthias/Workspaces/skiros2_ws/build/skiros2_skill/skiros2_skill/ros/skill_manager.py", line 385, in __init__
    self.sm = SkillManager(self, self.get_parameter('prefix').value, full_name, verbose=self.get_parameter('verbose').value)
  File "/home/matthias/Workspaces/skiros2_ws/build/skiros2_skill/skiros2_skill/nodes/skill_manager_node.py", line 7, in main
    node = SkillManagerNode()
  File "/home/matthias/Workspaces/skiros2_ws/install/skiros2_skill/lib/skiros2_skill/skill_manager_node", line 33, in <module>
    sys.exit(load_entry_point('skiros2-skill', 'console_scripts', 'skill_manager_node')())
  File "/usr/lib/python3.10/runpy.py", line 86, in _run_code
    exec(code, run_globals)
  File "/usr/lib/python3.10/runpy.py", line 196, in _run_module_as_main (Current frame)
    return _run_code(code, main_globals, None,
ValueError: Logger severity cannot be changed between calls