feat(fcm): Add live_activity_token to APNSConfig (#880)

* Add live_activity_token to `APNSConfig`, allowing you to specify this token for APNS messages.

This change introduces:
- Adding the `live_activity_token` field to the `APNSConfig` class
- Updated unit test to verify that the `live_activity_token` is correctly included in the encoded message

* Refactor and edit doc string

---------

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>

Author: jonathanedey

firebase_admin/_messaging_encoder.py

@@ -529,6 +529,8 @@ def encode_apns(cls, apns):
                 'APNSConfig.headers', apns.headers),
             'payload': cls.encode_apns_payload(apns.payload),
             'fcm_options': cls.encode_apns_fcm_options(apns.fcm_options),
+            'live_activity_token': _Validators.check_string(
+                'APNSConfig.live_activity_token', apns.live_activity_token),
         }
         return cls.remove_null_values(result)
 

firebase_admin/_messaging_utils.py

@@ -334,15 +334,17 @@ class APNSConfig:
         payload: A ``messaging.APNSPayload`` to be included in the message (optional).
         fcm_options: A ``messaging.APNSFCMOptions`` instance to be included in the message
             (optional).
+        live_activity_token: A live activity token string (optional).
 
     .. _APNS Documentation: https://developer.apple.com/library/content/documentation\
         /NetworkingInternet/Conceptual/RemoteNotificationsPG/CommunicatingwithAPNs.html
     """
 
-    def __init__(self, headers=None, payload=None, fcm_options=None):
+    def __init__(self, headers=None, payload=None, fcm_options=None, live_activity_token=None):
         self.headers = headers
         self.payload = payload
         self.fcm_options = fcm_options
+        self.live_activity_token = live_activity_token
 
 
 class APNSPayload:

tests/test_messaging.py

@@ -1094,7 +1094,8 @@ def test_apns_config(self):
             topic='topic',
             apns=messaging.APNSConfig(
                 headers={'h1': 'v1', 'h2': 'v2'},
-                fcm_options=messaging.APNSFCMOptions('analytics_label_v1')
+                fcm_options=messaging.APNSFCMOptions('analytics_label_v1'),
+                live_activity_token='test_token_string'
             ),
         )
         expected = {
@@ -1107,6 +1108,7 @@ def test_apns_config(self):
                 'fcm_options': {
                     'analytics_label': 'analytics_label_v1',
                 },
+                'live_activity_token': 'test_token_string',
             },
         }
         check_encoding(msg, expected)