url_encoding: Use user name instead of email in personal_narrow_url.

This commit updates the urls for personal narrow sent in email
notifications to be of form "{user_id}-{encoded_full_name}" to
make it consistent with the urls that we use for such narrows
in webapp which were recently updated in b4eddad for improving
performance. We encode the full name in the same way that we do in
webapp by replacing the url characters encoded by browser with "-".

zerver/lib/url_encoding.py

@@ -1,7 +1,8 @@
-from email.headerregistry import Address
 from typing import Any, Dict, List
 from urllib.parse import quote, urlsplit
 
+import re2
+
 from zerver.lib.topic import get_topic_from_message_info
 from zerver.models import Realm, Stream, UserProfile
 
@@ -21,8 +22,8 @@ def encode_stream(stream_id: int, stream_name: str) -> str:
 
 def personal_narrow_url(realm: Realm, sender: UserProfile) -> str:
     base_url = f"{realm.uri}/#narrow/pm-with/"
-    email_user = Address(addr_spec=sender.email).username.lower()
-    pm_slug = str(sender.id) + "-" + hash_util_encode(email_user)
+    encoded_user_name = re2.sub(r'[ "%\/<>`\p{C}]+', "-", sender.full_name)
+    pm_slug = str(sender.id) + "-" + encoded_user_name
     return base_url + pm_slug