Suggestion: init_vectorstore_table() should also create the schema

Hi there,
  This is just a suggestion: When using `init_vectorstore_table()` I had expected it to create the schema if it didn't exist.

```python
engine.init_vectorstore_table(
    schema_name="vector_store",
    overwrite_existing=True,
    table_name=table_name,
    vector_size=vector_size,
)
```

Please consider adopting this behavior. Cheers