Can now have multiple system actors

We also handle webfinger/activity serialization properly

api/funkwhale_api/federation/actors.py

@@ -0,0 +1,48 @@
+import requests
+
+from django.urls import reverse
+from django.conf import settings
+
+from dynamic_preferences.registries import global_preferences_registry
+
+from . import models
+
+
+def get_actor_data(actor_url):
+    response = requests.get(actor_url)
+    response.raise_for_status()
+    return response.json()
+
+
+SYSTEM_ACTORS = {
+    'library': {
+        'get_actor': lambda: models.Actor(**get_base_system_actor_arguments('library')),
+    }
+}
+
+
+def get_base_system_actor_arguments(name):
+    preferences = global_preferences_registry.manager()
+    return {
+        'preferred_username': name,
+        'domain': settings.FEDERATION_HOSTNAME,
+        'type': 'Person',
+        'name': '{}\'s library'.format(settings.FEDERATION_HOSTNAME),
+        'manually_approves_followers': True,
+        'url': reverse(
+            'federation:instance-actors-detail',
+            kwargs={'actor': name}),
+        'shared_inbox_url': reverse(
+            'federation:instance-actors-inbox',
+            kwargs={'actor': name}),
+        'inbox_url': reverse(
+            'federation:instance-actors-inbox',
+            kwargs={'actor': name}),
+        'outbox_url': reverse(
+            'federation:instance-actors-outbox',
+            kwargs={'actor': name}),
+        'public_key': preferences['federation__public_key'],
+        'summary': 'Bot account to federate with {}\'s library'.format(
+            settings.FEDERATION_HOSTNAME
+        ),
+    }