`ElasticsearchInferenceSparseRetriever` (ES inference for sparse)

[davidsbatista]

• Add a new Retriever or extend the ElasticsearchSparseEmbeddingRetriever to use inference_id + query in the sparse_vector query (e.g. _sparse_vector_retrieval with an inference mode, or a dedicated method).
• New retriever component: input query (text), config inference_id (e.g. ELSER); calls the document store’s inference-based sparse retrieval method.
• ES: sparse_vector query (inference_id + query).