Unable to use Pageant

[bgoewert]

Noticed that a method to use an ssh agent was added. But not a way to define what agent is being used, i.e. pageant.

Currently, #27 added a config.agent but is forced to use process.env.SSH_AUTH_SOCK.

As mentioned in #15, supposedly I can use pageant on Windows. But there is no way to set what agent I can use, at least from what I've seen.

src/tunnel.ts

if (serverInfo.ssh.useAgent) {
  if (!process.env.SSH_AUTH_SOCK) {
    throw new Error('not set SSH_AUTH_SOCK env variable');
  }

  config.agent = process.env.SSH_AUTH_SOCK;
}