Transition away from profiler fails on unsaved changes check

[jw3]

The logic looking at unsaved changes causes failure when navigating away from the profiler page.

1. Navigate to the profiler
2. Navigate away from the profiler
3. Observe stack trace

Traceback (most recent call last):
  File "/usr/lib64/python3.11/site-packages/fapolicy_analyzer/ui/main_window.py", line 479, in on_configAdminMenu_activate
    self.__pack_main_content(router(PAGE_SELECTION.CONFIG))
  File "/usr/lib64/python3.11/site-packages/fapolicy_analyzer/ui/main_window.py", line 180, in __pack_main_content
    if hasattr(self.__page, "_unsaved_changes") and self.__page._unsaved_changes:
       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/site-packages/events/events.py", line 93, in __getattr__
    raise EventsException("Event '%s' is not declared" % name)
events.events.EventsException: Event '_unsaved_changes' is not declared

main_window.py", line 180

ht: #916 (reply in thread)

#921

[jw3]

This issue was weird because it only failed on some UI pages. Looking at the events code

events.py 91

        if hasattr(self, '__events__'):
            if name not in self.__events__:
                raise EventsException("Event '%s' is not declared" % name)

So if the page had declared an __events__ list, the thing has to be in it, otherwise its happy to just introspect the properties of the object.