Move System and Member to separate files

src/pluralkit/system.py

@@ -0,0 +1,22 @@
+from datetime import datetime
+
+from collections.__init__ import namedtuple
+
+
+class System(namedtuple("System", ["id", "hid", "name", "description", "tag", "avatar_url", "created"])):
+    id: int
+    hid: str
+    name: str
+    description: str
+    tag: str
+    avatar_url: str
+    created: datetime
+
+    def to_json(self):
+        return {
+            "id": self.hid,
+            "name": self.name,
+            "description": self.description,
+            "tag": self.tag,
+            "avatar_url": self.avatar_url
+        }