couchbase: Add standard and semantic caches (#23607)

Thank you for contributing to LangChain!

**Description:** Add support for caching (standard + semantic) LLM
responses using Couchbase


- [x] **Add tests and docs**: If you're adding a new integration, please
include
1. a test for the integration, preferably unit tests that do not rely on
network access,
2. an example notebook showing its use. It lives in
`docs/docs/integrations` directory.


- [x] **Lint and test**: Run `make format`, `make lint` and `make test`
from the root of the package(s) you've modified. See contribution
guidelines for more: https://python.langchain.com/docs/contributing/

Additional guidelines:
- Make sure optional dependencies are imported within a function.
- Please do not add dependencies to pyproject.toml files (even optional
ones) unless they are required for unit tests.
- Most PRs should not touch more than one package.
- Changes should be backwards compatible.
- If you are adding something to community, do not re-import it in
langchain.

If no one reviews your PR within a few days, please @-mention one of
baskaryan, efriis, eyurtsev, ccurme, vbarda, hwchase17.

---------

Co-authored-by: Nithish Raghunandanan <nithishr@users.noreply.github.com>
Co-authored-by: Erick Friis <erick@langchain.dev>

libs/partners/couchbase/langchain_couchbase/__init__.py

@@ -2,4 +2,6 @@ from langchain_couchbase.vectorstores import CouchbaseVectorStore
 
 __all__ = [
     "CouchbaseVectorStore",
+    "CouchbaseCache",
+    "CouchbaseSemanticCache",
 ]