Currently `SlackWebhookHook` gets the token from `extra` but it would be more secure and intuitive to have it in password.

https://github.com/apache/airflow/blob/4fb5c017fe5ca41ed95547a857c9c39efc4f1476/airflow/providers/slack/hooks/slack_webhook.py
tests/providers/slack/hooks/test_slack_webhook.py
db.merge_conn(
            Connection(
                conn_id='slack-webhook-default',
                conn_type='http',
                extra='{"webhook_token": "your_token_here"}',
            )
        )
        db.merge_conn(
            Connection(
                conn_id='slack-webhook-url',
                conn_type='http',
                host='https://hooks.slack.com/services/T000/B000/XXX',
            )
        )
        db.merge_conn(
            Connection(
                conn_id='slack-webhook-host', conn_type='http', host='https://hooks.slack.com/services/T000/'
            )
        )
    def test_get_token_manual_token(self):
        
        manual_token = 'manual_token_here'
        hook = SlackWebhookHook(webhook_token=manual_token)
        
        webhook_token = hook._get_token(manual_token, None)
        
        self.assertEqual(webhook_token, manual_token)
    def test_get_token_conn_id(self):