add route for admins to list all groups

unwind/web.py

@@ -234,6 +234,13 @@ async def load_imdb_user_ratings(request):
     return JSONResponse({"new_ratings": [asplain(r) for r in ratings]})
 
 
+@route("/groups")
+@requires(["authenticated", "admin"])
+async def list_groups(request):
+    groups = await db.get_all(Group)
+    return JSONResponse([asplain(g) for g in groups])
+
+
 @route("/groups", methods=["POST"])
 @requires(["authenticated", "admin"])
 async def add_group(request):