Allow setting TLS settings on the underlying HTTPS agent

[sidfarkus]

Currently the settings for a custom certificate or two-way SSL are implemented on the IConnectionOptions interface but they don't surface back up to an object that the user of the library can easily manipulate; for example in ConnectionOptions. I think these options should be settable when establishing a new connection in https://github.com/databricks/databricks-sql-nodejs/blob/main/lib/DBSQLClient.ts#L120C16-L120C23

A workaround is to bypass the 'private' protections on DBSQLClient.getConnectionOptions but that is non-ideal.