community: add InfinityRerank (#27043)

**Description:** 

- Add a Reranker for Infinity server.

**Dependencies:** 

This wrapper uses
[infinity_client](https://github.com/michaelfeil/infinity/tree/main/libs/client_infinity/infinity_client)
to connect to an Infinity server.

**Tests and docs**

- integration test: test_infinity_rerank.py
- example notebook: infinity_rerank.ipynb
[here](https://github.com/baptiste-pasquier/langchain/blob/feat/infinity-rerank/docs/docs/integrations/document_transformers/infinity_rerank.ipynb)

---------

Co-authored-by: Erick Friis <erick@langchain.dev>

libs/community/tests/integration_tests/document_compressors/test_infinity_rerank.py

@@ -0,0 +1,32 @@
+from langchain_core.documents import Document
+
+from langchain_community.document_compressors.infinity_rerank import (
+    InfinityRerank,
+)
+
+
+def test_rerank() -> None:
+    reranker = InfinityRerank()
+    docs = [
+        Document(
+            page_content=(
+                "This is a document not related to the python package infinity_emb, "
+                "hence..."
+            )
+        ),
+        Document(page_content="Paris is in France!"),
+        Document(
+            page_content=(
+                "infinity_emb is a package for sentence embeddings and rerankings using"
+                " transformer models in Python!"
+            )
+        ),
+        Document(page_content="random text for nothing"),
+    ]
+    compressed = reranker.compress_documents(
+        query="What is the python package infinity_emb?",
+        documents=docs,
+    )
+
+    assert len(compressed) == 3, "default top_n is 3"
+    assert compressed[0].page_content == docs[2].page_content, "rerank works"