Add timeout parameter to context.call

[CahidArda]

Adds timeout parameter to context.call:

context.call("my-step", {
  url,
  body,
  headers: { "my-header": "my-value" },
  method: "PATCH",
  retries: retries,
  timeout: 30,
});

Also add an error when step name is undefined or empty string.

getHeaders method is becoming a little to crowded, but we are planning to refactor that in the future.

[fahreddinozcan]

Can we add the unit to jsdocs here?

[joschan21]

let's make the error message a bit more clear, otherwise LGTM