feat: allow Python and Typescript users to create Sessions (#2530)

## Summary
- Exposes `Session` in Python and Typescript so users can set the
`index_cache_size_bytes` and `metadata_cache_size_bytes`
* The `Session` is attached to the `Connection`, and thus shared across
all tables in that connection.
- Adds deprecation warnings for table-level cache configuration


🤖 Generated with [Claude Code](https://claude.ai/code)

---------

Co-authored-by: Claude <noreply@anthropic.com>

docs/src/js/classes/Session.md

@@ -0,0 +1,84 @@
+[**@lancedb/lancedb**](../README.md) • **Docs**
+
+***
+
+[@lancedb/lancedb](../globals.md) / Session
+
+# Class: Session
+
+A session for managing caches and object stores across LanceDB operations.
+
+Sessions allow you to configure cache sizes for index and metadata caches,
+which can significantly impact performance for large datasets.
+
+## Constructors
+
+### new Session()
+
+```ts
+new Session(indexCacheSizeBytes?, metadataCacheSizeBytes?): Session
+```
+
+Create a new session with custom cache sizes.
+
+# Parameters
+
+- `index_cache_size_bytes`: The size of the index cache in bytes.
+  Defaults to 6GB if not specified.
+- `metadata_cache_size_bytes`: The size of the metadata cache in bytes.
+  Defaults to 1GB if not specified.
+
+#### Parameters
+
+* **indexCacheSizeBytes?**: `null` \| `bigint`
+
+* **metadataCacheSizeBytes?**: `null` \| `bigint`
+
+#### Returns
+
+[`Session`](Session.md)
+
+## Methods
+
+### approxNumItems()
+
+```ts
+approxNumItems(): number
+```
+
+Get the approximate number of items cached in the session.
+
+#### Returns
+
+`number`
+
+***
+
+### sizeBytes()
+
+```ts
+sizeBytes(): bigint
+```
+
+Get the current size of the session caches in bytes.
+
+#### Returns
+
+`bigint`
+
+***
+
+### default()
+
+```ts
+static default(): Session
+```
+
+Create a session with default cache sizes.
+
+This is equivalent to creating a session with 6GB index cache
+and 1GB metadata cache.
+
+#### Returns
+
+[`Session`](Session.md)