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)

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

rust/lancedb/src/lib.rs

@@ -290,3 +290,7 @@ impl Display for DistanceType {
 
 /// Connect to a database
 pub use connection::connect;
+
+/// Re-export Lance Session and ObjectStoreRegistry for custom session creation
+pub use lance::session::Session;
+pub use lance_io::object_store::ObjectStoreRegistry;