wip trace cache and middleware

AUTHENTICATED_PARTICIPANTS_CAN_EDIT_DISPLAY_NAME was only enforced at
LiveKit token generation and by hiding the name field in the frontend.
The `rooms/{id}/rename/` endpoint never checked it, so any authenticated
user with a valid room token could rename themselves via the API even
when the self-hoster had disabled it.

Return 403 from the rename action for authenticated users when the
setting is disabled, mirroring the `can_edit` rule in
`core.utils.generate_token`. Anonymous participants are unaffected, as
they have no account name to fall back on.

Add tests covering the disabled/enabled cases for authenticated users
and the anonymous exception.

src/backend/meet/settings.py

@@ -1211,7 +1211,13 @@ class Base(Configuration):
                 dsn=cls.SENTRY_DSN,
                 environment=cls.__name__.lower(),  # build, test, development, production
                 release=get_release(),
-                integrations=[DjangoIntegration()],
+                integrations=[
+                    DjangoIntegration(
+                        transaction_style="url",
+                        middleware_spans=True,
+                        cache_spans=True,
+                    )
+                ],
             )
             sentry_sdk.set_tag("application", "backend")