Resolve "Allow apps to register OAuth scopes"

Closes #495 (closed)

aleksis/core/util/apps.py

 from importlib import metadata
-from typing import Any, Optional, Sequence
+from typing import TYPE_CHECKING, Any, Optional, Sequence
 
 import django.apps
 from django.contrib.auth.signals import user_logged_in, user_logged_out
@@ -12,6 +12,9 @@ from spdx_license_list import LICENSES
 
 from .core_helpers import copyright_years
 
+if TYPE_CHECKING:
+    from oauth2_provider.models import AbstractApplication
+
 
 class AppConfig(django.apps.AppConfig):
     """An extended version of DJango's AppConfig container."""
@@ -214,6 +217,30 @@ class AppConfig(django.apps.AppConfig):
         """
         pass
 
+    def get_all_scopes(self) -> dict[str, str]:
+        """Return all OAuth scopes and their descriptions for this app."""
+        return {}
+
+    def get_available_scopes(
+        self,
+        application: Optional["AbstractApplication"] = None,
+        request: Optional[HttpRequest] = None,
+        *args,
+        **kwargs,
+    ) -> list[str]:
+        """Return a list of all OAuth scopes available to the request and application."""
+        return list(self.get_all_scopes().keys())
+
+    def get_default_scopes(
+        self,
+        application: Optional["AbstractApplication"] = None,
+        request: Optional[HttpRequest] = None,
+        *args,
+        **kwargs,
+    ) -> list[str]:
+        """Return a list of all OAuth scopes to always include for this request and application."""
+        return []
+
     def _maintain_default_data(self):
         from django.contrib.auth.models import Permission
         from django.contrib.contenttypes.models import ContentType