Feature request: `autocommit` as connector `__init__` property

Currently, to set `autocommit` to `True`, we have to explicitly run:

```
connection.autocommit = True
```

Is there a way to pass `autocommit` as a property to the connector constructor? Something like:

```
redshift_connector.connect({
autocommit=True,
**connection_params
})
```

We are trying to build an SQL client for our customers with Redshift as one of the underlying data-sources. It would be much cleaner this way avoiding unnecessary if-else conditioning.

Start at the redshift_connector.connect entry point and trace how connection parameters reach the connection object, then inspect the existing connection.autocommit behavior. Done means the connector accepts autocommit during construction and preserves the current explicit assignment behavior; add or update the relevant connector tests to cover the constructor option.

索引モデルが issue の本文から書いたものです。