add vertex prod features (#10910)

- chat vertex async
- vertex stream
- vertex full generation info
- vertex use server-side stopping
- model garden async
- update docs for all the above

in follow up will add
[] chat vertex full generation info
[] chat vertex retries
[] scheduled tests

docs/extras/integrations/platforms/google.mdx

@@ -2,6 +2,35 @@
 
 All functionality related to Google Platform
 
+## LLMs
+
+### Vertex AI
+
+Access PaLM LLMs like `text-bison` and `code-bison` via Google Cloud.
+
+```python
+from langchain.llms import VertexAI
+```
+
+### Model Garden
+
+Access PaLM and hundreds of OSS models via Vertex AI Model Garden.
+
+```python
+from langchain.llms import VertexAIModelGarden
+```
+
+## Chat models
+
+### Vertex AI
+
+Access PaLM chat models like `chat-bison` and `codechat-bison` via Google Cloud.
+
+```python
+from langchain.chat_models import ChatVertexAI
+```
+
+
 ## Document Loader
 ### Google BigQuery