Provide option to set `keyboard-interactive` handler

[ultram4rine]

Hi, I guess it would be helpful to have an option to provide handler for keyboard-interactive auth.

tunnel-ssh/index.js

Lines 38 to 45 in a4e74ba

	async function createSSHConnection(config) {
	return new Promise(function (resolve, reject) {
	let conn = new Client();
	conn.on('ready', () => resolve(conn));
	conn.on('error', reject);
	conn.connect(config);
	});
	}

Something like:

async function createSSHConnection(config, keyboardInteractiveHandler) {
    return new Promise(function (resolve, reject) {
        let conn = new Client();
        conn.on('ready', () => resolve(conn));
        conn.on('error', reject);
        conn.on('keyboard-interactive', keyboardInteractiveHandler)
        conn.connect(config);
    });
}