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

docs/static/frigate-api.yaml

@@ -2131,7 +2131,7 @@ paths:
           required: false
           schema:
             type: string
-            default: utc
+            default: UTC
             title: Timezone
       responses:
         '200':
@@ -3266,7 +3266,7 @@ paths:
             anyOf:
               - type: string
               - type: 'null'
-            default: utc
+            default: UTC
             title: Timezone
       responses:
         '200':
@@ -4666,7 +4666,7 @@ paths:
             anyOf:
               - type: string
               - type: 'null'
-            default: utc
+            default: UTC
             title: Timezone
       responses:
         '200':
@@ -4928,7 +4928,7 @@ paths:
             anyOf:
               - type: string
               - type: 'null'
-            default: utc
+            default: UTC
             title: Timezone
         - name: min_score
           in: query
@@ -5008,7 +5008,7 @@ paths:
             anyOf:
               - type: string
               - type: 'null'
-            default: utc
+            default: UTC
             title: Timezone
         - name: has_clip
           in: query
@@ -7367,7 +7367,7 @@ paths:
           required: false
           schema:
             type: string
-            default: utc
+            default: UTC
             title: Timezone
         - name: cameras
           in: query
@@ -7417,7 +7417,7 @@ paths:
           required: false
           schema:
             type: string
-            default: utc
+            default: UTC
             title: Timezone
       responses:
         '200':