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/api/event.py

@@ -612,7 +612,7 @@ def set_retain(id):
 
 @EventBp.route("/events/<id>/plus", methods=("POST",))
 def send_to_plus(id):
-    if not current_app.plus_api.is_active():
+    if not current_app.frigate_config.plus_api.is_active():
         message = "PLUS_API_KEY environment variable is not set"
         logger.error(message)
         return make_response(
@@ -680,7 +680,7 @@ def send_to_plus(id):
         )
 
     try:
-        plus_id = current_app.plus_api.upload_image(image, event.camera)
+        plus_id = current_app.frigate_config.plus_api.upload_image(image, event.camera)
     except Exception as ex:
         logger.exception(ex)
         return make_response(
@@ -696,7 +696,7 @@ def send_to_plus(id):
         box = event.data["box"]
 
         try:
-            current_app.plus_api.add_annotation(
+            current_app.frigate_config.plus_api.add_annotation(
                 event.plus_id,
                 box,
                 event.label,
@@ -720,7 +720,7 @@ def send_to_plus(id):
 
 @EventBp.route("/events/<id>/false_positive", methods=("PUT",))
 def false_positive(id):
-    if not current_app.plus_api.is_active():
+    if not current_app.frigate_config.plus_api.is_active():
         message = "PLUS_API_KEY environment variable is not set"
         logger.error(message)
         return make_response(
@@ -769,7 +769,7 @@ def false_positive(id):
     )
 
     try:
-        current_app.plus_api.add_false_positive(
+        current_app.frigate_config.plus_api.add_false_positive(
             event.plus_id,
             region,
             box,