management: Add library for getting a client object.

This is to be used in some analytics features we're adding in the near
future.

zerver/lib/management.py

@@ -8,7 +8,7 @@ from django.core.exceptions import MultipleObjectsReturned
 from django.core.management.base import BaseCommand, CommandError
 from typing import Any, Dict, Optional, List
 
-from zerver.models import Realm, UserProfile
+from zerver.models import Realm, UserProfile, Client, get_client
 
 def is_integer_string(val: str) -> bool:
     try:
@@ -120,3 +120,7 @@ You can use the command list_realms to find ID of the realms in this server."""
                                "to specify which one to modify.")
         except UserProfile.DoesNotExist:
             raise CommandError("This Zulip server does not contain a user with email '%s'" % (email,))
+
+    def get_client(self) -> Client:
+        """Returns a Zulip Client object to be used for things done in management commands"""
+        return get_client("ZulipServer")