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/interfaces/ConnectionOptions.md

@@ -70,6 +70,17 @@ Defaults to 'us-east-1'.
 
 ***
 
+### session?
+
+```ts
+optional session: Session;
+```
+
+(For LanceDB OSS only): the session to use for this connection. Holds
+shared caches and other session-specific state.
+
+***
+
 ### storageOptions?
 
 ```ts

docs/src/js/interfaces/OpenTableOptions.md

@@ -8,7 +8,7 @@
 
 ## Properties
 
-### indexCacheSize?
+### ~~indexCacheSize?~~
 
 ```ts
 optional indexCacheSize: number;
@@ -16,6 +16,11 @@ optional indexCacheSize: number;
 
 Set the size of the index cache, specified as a number of entries
 
+#### Deprecated
+
+Use session-level cache configuration instead.
+Create a Session with custom cache sizes and pass it to the connect() function.
+
 The exact meaning of an "entry" will depend on the type of index:
 - IVF: there is one entry for each IVF partition
 - BTREE: there is one entry for the entire index