Handle SIGINT with forkserver (#18860)

* Pass stopevent from main start

* Share stop event across processes

* preload modules

* remove explicit os._exit call

---------

Co-authored-by: Josh Hawkins <32435876+hawkeye217@users.noreply.github.com>

frigate/output/output.py

@@ -5,6 +5,7 @@ import logging
 import os
 import shutil
 import threading
+from multiprocessing.synchronize import Event as MpEvent
 from wsgiref.simple_server import make_server
 
 from ws4py.server.wsgirefserver import (
@@ -72,8 +73,8 @@ def check_disabled_camera_update(
 
 
 class OutputProcess(FrigateProcess):
-    def __init__(self, config: FrigateConfig) -> None:
-        super().__init__(name="frigate.output", daemon=True)
+    def __init__(self, config: FrigateConfig, stop_event: MpEvent) -> None:
+        super().__init__(stop_event, name="frigate.output", daemon=True)
         self.config = config
 
     def run(self) -> None: