community[minor]: Sambanova llm integration (#20955)

- **Description:** Added [Sambanova systems](https://sambanova.ai/)
integration, including sambaverse and sambastudio LLMs
- **Dependencies:**   sseclient-py  (optional)

---------

Co-authored-by: Bagatur <22008038+baskaryan@users.noreply.github.com>
Co-authored-by: Bagatur <baskaryan@gmail.com>

libs/community/tests/integration_tests/llms/test_sambanova.py

@@ -0,0 +1,28 @@
+"""Test sambanova API wrapper.
+
+In order to run this test, you need to have an sambaverse api key, 
+and a sambaverse base url, project id, endpoint id, and api key.
+You'll then need to set SAMBAVERSE_API_KEY, SAMBASTUDIO_BASE_URL,
+SAMBASTUDIO_PROJECT_ID, SAMBASTUDIO_ENDPOINT_ID, and SAMBASTUDIO_API_KEY
+environment variables.
+"""
+from langchain_community.llms.sambanova import SambaStudio, Sambaverse
+
+
+def test_sambaverse_call() -> None:
+    """Test simple non-streaming call to sambaverse."""
+    llm = Sambaverse(
+        sambaverse_model_name="Meta/llama-2-7b-chat-hf",
+        model_kwargs={"select_expert": "llama-2-7b-chat-hf"},
+    )
+    output = llm.invoke("What is LangChain")
+    assert output
+    assert isinstance(output, str)
+
+
+def test_sambastudio_call() -> None:
+    """Test simple non-streaming call to sambaverse."""
+    llm = SambaStudio()
+    output = llm.invoke("What is LangChain")
+    assert output
+    assert isinstance(output, str)