feat: add Momento as a standard cache and chat message history provider (#5221)

# Add Momento as a standard cache and chat message history provider

This PR adds Momento as a standard caching provider. Implements the
interface, adds integration tests, and documentation. We also add
Momento as a chat history message provider along with integration tests,
and documentation.

[Momento](https://www.gomomento.com/) is a fully serverless cache.
Similar to S3 or DynamoDB, it requires zero configuration,
infrastructure management, and is instantly available. Users sign up for
free and get 50GB of data in/out for free every month.

## Before submitting

✅ We have added documentation, notebooks, and integration tests
demonstrating usage.

Co-authored-by: Dev 2049 <dev.dev2049@gmail.com>

docs/integrations/momento.md

@@ -0,0 +1,53 @@
+# Momento
+
+This page covers how to use the [Momento](https://gomomento.com) ecosystem within LangChain.
+It is broken into two parts: installation and setup, and then references to specific Momento wrappers.
+
+## Installation and Setup
+
+- Sign up for a free account [here](https://docs.momentohq.com/getting-started) and get an auth token
+- Install the Momento Python SDK with `pip install momento`
+
+## Wrappers
+
+### Cache
+
+The Cache wrapper allows for [Momento](https://gomomento.com) to be used as a serverless, distributed, low-latency cache for LLM prompts and responses.
+
+#### Standard Cache
+
+The standard cache is the go-to use case for [Momento](https://gomomento.com) users in any environment.
+
+Import the cache as follows:
+
+```python
+from langchain.cache import MomentoCache
+```
+
+And set up like so:
+
+```python
+from datetime import timedelta
+from momento import CacheClient, Configurations, CredentialProvider
+import langchain
+
+# Instantiate the Momento client
+cache_client = CacheClient(
+    Configurations.Laptop.v1(),
+    CredentialProvider.from_environment_variable("MOMENTO_AUTH_TOKEN"),
+    default_ttl=timedelta(days=1))
+
+# Choose a Momento cache name of your choice
+cache_name = "langchain"
+
+# Instantiate the LLM cache
+langchain.llm_cache = MomentoCache(cache_client, cache_name)
+```
+
+### Memory
+
+Momento can be used as a distributed memory store for LLMs.
+
+#### Chat Message History Memory
+
+See [this notebook](../modules/memory/examples/momento_chat_message_history.ipynb) for a walkthrough of how to use Momento as a memory store for chat message history.