ssh key problems

[brunovianna]

1. node-ssh only works with keys generated with the flag -m PEM see here https://github.com/microsoft/azure-pipelines-tasks/issues/8818#issuecomment-465671721
2. there should be a way of selecting other key and not using the default ${homedir}/.ssh/id_rsa
3. the ssh error is not being shown because
   3a. json parsing of the error is returning an empty json
   3b. i think the variable retries is never set, so it just returns with a reject with a blank error json