Move more things out of FrigateApp (#13897)

* Moved FrigateApp.init_config() into FrigateConfig.load()

* Move frigate config loading into main

* Store PlusApi in FrigateConfig

* Register SIGTERM handler in main

* Ensure logging is setup during config parsing

* Removed pointless try

* Moved config initialization out of FrigateApp

* Made FrigateApp.shm_frame_count into a function

* Removed log calls from signal handlers

python's logging calls are not re-entrant, which caused at least one of
these to deadlock randomly.

* Reopen stdout/err on process fork

This helps avoid deadlocks (https://github.com/python/cpython/issues/91776).

* Make mypy happy

* Whoops. I might have forgotten to save.

Truly an amateur mistake.

* Always call FrigateApp.stop()

frigate/output/output.py

@@ -38,7 +38,6 @@ def output_frames(
     stop_event = mp.Event()
 
     def receiveSignal(signalNumber, frame):
-        logger.debug(f"Output frames process received signal {signalNumber}")
         stop_event.set()
 
     signal.signal(signal.SIGTERM, receiveSignal)