model: Add is_user_muted method.

Test added.

Author: rsashank

tests/model/test_model.py

@@ -4112,6 +4112,17 @@ def test_is_muted_topic(
 
         assert return_value == is_muted
 
+    @pytest.mark.parametrize(
+        "user, is_muted",
+        [
+            case(1, False, id="unmuted_user"),
+            case(2, True, id="muted_user"),
+        ],
+    )
+    def test_is_muted_user(self, user, is_muted, model):
+        model._muted_users = {2}
+        assert model.is_muted_user(user) == is_muted
+
     @pytest.mark.parametrize(
         "unread_topics, current_topic, next_unread_topic",
         [

zulipterminal/model.py

@@ -957,6 +957,9 @@ def is_muted_topic(self, stream_id: int, topic: str) -> bool:
         topic_to_search = (stream_name, topic)
         return topic_to_search in self._muted_topics
 
+    def is_muted_user(self, user_id: int) -> bool:
+        return user_id in self._muted_users
+
     def stream_topic_from_message_id(
         self, message_id: int
     ) -> Optional[Tuple[int, str]]: