[JENKINS-66465] Support implementations of SSHUserPrivateKey for Wind…

[Dohbedoh]

…ows Configuration

[JENKINS-66465]https://issues.jenkins.io/browse/JENKINS-66465):

• Allow selection for more implementations of SSHUserPrivateKey as as far as I understand this is supported.
• Refactor the usage StandardListBoxModel to not using deprecated APIs
• Added tests for HTTP and SSH credentials selection

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
• Link to relevant issues in GitHub or Jira
• Link to relevant pull requests, esp. upstream and downstream changes
• Ensure you have provided tests - that demonstrates feature works or fixes the issue

[Dohbedoh]

ping @donmccasland