community[patch]: Fix MLX LLM Stream (#20575)

Closes #20561

This PR fixes MLX LLM stream `AttributeError`. 

Recently, `mlx-lm` changed the token decoding logic, which affected the
LC+MLX integration.

Additionally, I made minor fixes such as: docs example broken link and
enforcing pipeline arguments (max_tokens, temp and etc) for invoke.
   
- **Issue:** #20561
    
- **Twitter handle:** @Prince_Canuma

docs/docs/integrations/chat/mlx.ipynb

@@ -9,7 +9,7 @@
     "This notebook shows how to get started using `MLX` LLM's as chat models.\n",
     "\n",
     "In particular, we will:\n",
-    "1. Utilize the [MLXPipeline](https://github.com/langchain-ai/langchain/blob/master/libs/langchain/langchain/llms/mlx_pipelines.py), \n",
+    "1. Utilize the [MLXPipeline](https://github.com/langchain-ai/langchain/blob/master/libs/community/langchain_community/llms/mlx_pipeline.py), \n",
     "2. Utilize the `ChatMLX` class to enable any of these LLMs to interface with LangChain's [Chat Messages](https://python.langchain.com/docs/modules/model_io/chat/#messages) abstraction.\n",
     "3. Demonstrate how to use an open-source LLM to power an `ChatAgent` pipeline\n"
    ]