Refactor old no_other_instance_running() into handle_edmc_callback_or_foregrounding()

The actual duplicate process checks *used* to be done in this function,
but no longer are.  Instead it's now specifically performing the "is
this an edmc:// auth callback?" check, including the foreground of the
extant process if needs be.

EDMarketConnector.py

@@ -71,11 +71,9 @@ if __name__ == '__main__':  # noqa: C901
     if args.force_localserver_for_auth:
         config.set_auth_force_localserver()
 
-    def no_other_instance_running() -> bool:  # noqa: CCR001
+    def handle_edmc_callback_or_foregrounding():  # noqa: CCR001
         """
-        Ensure only one copy of the app is running for the configured journal directory.
-
-        :returns: True if we are the single instance, else False.
+        Handle any edmc:// auth callback, else foreground existing window.
         """
         logger.trace('Begin...')
 
@@ -162,9 +160,7 @@ if __name__ == '__main__':  # noqa: C901
                 # Ref: <https://docs.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-enumwindows>
                 EnumWindows(enumwindowsproc, 0)
 
-                return False  # Another instance is running
-
-        return True
+        return
 
     def already_running_popup():
         """Create the "already running" popup."""
@@ -192,8 +188,9 @@ if __name__ == '__main__':  # noqa: C901
     journal_lock = JournalLock()
     locked = journal_lock.obtain_lock()
 
-    if journal_lock.journal_dir_lockfile:
-        if not no_other_instance_running():
+    handle_edmc_callback_or_foregrounding()
+
+    if not locked:
         # There's a copy already running.
 
         logger.info("An EDMarketConnector.exe process was already running, exiting.")