Providing SSHClient on onAuthenticated callback and Environment Variables feature

[busslina]

Before this, I have to do this trick with a Completer as we can't use client on its own definition:

final socket = await SSHSocket.connect(_remoteSshHost, 22);
final authenticatedCompleter = Completer();
final client = SSHClient(
  socket,
  username: _remoteSshUser,
  identities: SSHKeyPair.fromPem(
    cc.read(sshPrivateKeyFileCapsule).readAsStringSync(),
  ),
  onAuthenticated: () {
    authenticatedCompleter.complete();
  },
);
print('Authenticating to SSH repository');

await authenticatedCompleter.future;

[busslina]

The authenticated feature was coded before knowing I have client.authenticated way to achieve my goal but I think it's also productive to have available the client there.