Community: Fuse HuggingFace Endpoint-related classes into one (#17254)

## Description
Fuse HuggingFace Endpoint-related classes into one:
-
[HuggingFaceHub](5ceaf784f3/libs/community/langchain_community/llms/huggingface_hub.py)
-
[HuggingFaceTextGenInference](5ceaf784f3/libs/community/langchain_community/llms/huggingface_text_gen_inference.py)
- and
[HuggingFaceEndpoint](5ceaf784f3/libs/community/langchain_community/llms/huggingface_endpoint.py)

Are fused into
- HuggingFaceEndpoint

## Issue
The deduplication of classes was creating a lack of clarity, and
additional effort to develop classes leads to issues like [this
hack](5ceaf784f3/libs/community/langchain_community/llms/huggingface_endpoint.py (L159)).

## Dependancies

None, this removes dependancies.

## Twitter handle

If you want to post about this: @AymericRoucher

---------

Co-authored-by: Bagatur <baskaryan@gmail.com>

libs/community/langchain_community/llms/huggingface_hub.py

@@ -1,6 +1,7 @@
 import json
 from typing import Any, Dict, List, Mapping, Optional
 
+from langchain_core._api.deprecation import deprecated
 from langchain_core.callbacks import CallbackManagerForLLMRun
 from langchain_core.language_models.llms import LLM
 from langchain_core.pydantic_v1 import Extra, root_validator
@@ -19,8 +20,10 @@ VALID_TASKS_DICT = {
 }
 
 
+@deprecated("0.0.21", removal="0.2.0", alternative="HuggingFaceEndpoint")
 class HuggingFaceHub(LLM):
     """HuggingFaceHub  models.
+    ! This class is deprecated, you should use HuggingFaceEndpoint instead.
 
     To use, you should have the ``huggingface_hub`` python package installed, and the
     environment variable ``HUGGINGFACEHUB_API_TOKEN`` set with your API token, or pass