Fix various warnings and deprecations (#23641)

* Migrate to fastapi lifespan for startup events

The `on_event` style decorator is deprecated

https://fastapi.tiangolo.com/advanced/events/

* Migrate to pydantic TypeAdapter

https://pydantic.dev/docs/validation/2.12/get-started/migration/#introduction-of-typeadapter

* Replace pytz with native tz-aware objects and zoneinfo library

Supported from Python 3.9, see https://peps.python.org/pep-0615/. Also
https://blog.ganssle.io/articles/2019/11/utcnow.html.

Also provide tzdata as new dependency to supplement systems without local
tzdata information.

* Provide lookup for normalized timezone names

This provides a helper to look up the correct timezone name independent
of the casing of the given timezone name.

* Test timezone naming normalization and error handling

frigate/api/defs/query/app_query_parameters.py

@@ -7,4 +7,4 @@ class AppTimelineHourlyQueryParameters(BaseModel):
     after: float | None = None
     before: float | None = None
     limit: int | None = 200
-    timezone: str | None = "utc"
+    timezone: str | None = "UTC"