feat(python): catch all exceptions thrown through fastapi route paths

This commit does quite a bit:
- Catches unhandled exceptions raised in the route handler and
  produces a 500 Internal Server Error Arch-themed response.
- Each unhandled exception causes a notification to be sent to new
  `notifications.postmaster` email with a "Traceback ID."
- Traceback ID is logged to the server along with the traceback which
  caused the 500: `docker-compose logs fastapi | grep '<traceback_id>'`
- If `options.traceback` is set to `1`, traceback is displayed in
  the new 500.html template.

Signed-off-by: Kevin Morris <kevr@0cost.org>

po/aurweb.pot

@@ -2304,3 +2304,20 @@ msgstr ""
 #: aurweb/packages/requests.py
 msgid "No due existing orphan requests to accept for %s."
 msgstr ""
+
+#: aurweb/asgi.py
+msgid "Internal Server Error"
+msgstr ""
+
+#: templates/errors/500.html
+msgid "A fatal error has occurred."
+msgstr ""
+
+#: templates/errors/500.html
+msgid "Details have been logged and will be reviewed by the postmaster "
+"posthaste. We apologize for any inconvenience this may have caused."
+msgstr ""
+
+#: aurweb/scripts/notify.py
+msgid "AUR Server Error"
+msgstr ""