partners: add 'model' alias for consistency in embedding classes (#28374)

**Description:** This PR introduces a `model` alias for the embedding
classes that contain the attribute `model_name`, to ensure consistency
across the codebase, as suggested by a moderator in a previous PR. The
change aligns the usage of attribute names across the project (see for
example
[here](65deeddd5d/libs/partners/groq/langchain_groq/chat_models.py (L304))).
**Issue:** This PR addresses the suggestion from the review of issue
#28269.
**Dependencies:**  None

---------

Co-authored-by: Eugene Yurtsev <eyurtsev@gmail.com>
Co-authored-by: Erick Friis <erick@langchain.dev>

libs/partners/huggingface/langchain_huggingface/embeddings/huggingface.py

@@ -26,7 +26,7 @@ class HuggingFaceEmbeddings(BaseModel, Embeddings):
             )
     """
 
-    model_name: str = DEFAULT_MODEL_NAME
+    model_name: str = Field(default=DEFAULT_MODEL_NAME, alias="model")
     """Model name to use."""
     cache_folder: Optional[str] = None
     """Path to store models. 
@@ -68,6 +68,7 @@ class HuggingFaceEmbeddings(BaseModel, Embeddings):
     model_config = ConfigDict(
         extra="forbid",
         protected_namespaces=(),
+        populate_by_name=True,
     )
 
     def _embed(