Throw error on failed request

[srhmgn]

Using the library, I noticed I was not getting an error in the scenario where I was using the client with a missing or incorrect token:

  const jira = new Jira({
      protocol: "https",
      host: "jira.somehost.com",
      username: "valid@username.com",
      password: "invalid-token",
  });

const res = await jira.searchJira('project = COOLPROJECT');

Instead of throwing an error, res is the string "Basic authentication with passwords is deprecated. For more information, see: https://developer.atlassian.com/cloud/confluence/deprecation-notice-basic-auth/"

This PR updates the logic in the doRequest and request functions to throw an error if:

• postman-request fails with an error
• request has a status code in the 400s or 500s

I used a tool called rewire to mock postman-request for testing and updated some related tests to use rewire as well.