[JENKINS-48949] - Make the plugin testable in PCT with JEP-200

[oleg-nenashev]

Work in progress PR...

• Make the plugin runnable in PCT
• Add Jenkinsfile
• Reproduce the issue in PCT and actually fix it IF the reporter provides repro steps. Confirmed, no issue
• Use Apache HttpComponents Client 4.x API instead of bundled libs

https://issues.jenkins-ci.org/browse/JENKINS-48949

@reviewbybees @jglick

[oleg-nenashev]

After code inspection I was unable to find the issue cause. I suspect that the issue report is incorrect, but I need stacktraces to confirm. This PR can be reviewed and integrated in the current state

[ghost]

This pull request originates from a CloudBees employee. At CloudBees, we require that all pull requests be reviewed by other CloudBees employees before we seek to have the change accepted. If you want to learn more about our process please see this explanation.

[oleg-nenashev]

@reviewbybees done

[oleg-nenashev]

@Brantone ping

[oleg-nenashev]

Thanks a lot @mezpahlan !