Generating plugins lock file

[aSky17]

fixes #488
plugins-lock.txt or plugins-lock.yaml file is the full list of plugins generated at a point in time with a specific Jenkins version and includes the plugins declared by the user and all the dependencies of those plugins.

plugins-lock.txt or plugins-lock.yaml file describe all the plugins and versions that were read from the Jenkins update center at the time the command was executed.

A plugins-lock.txt or plugins-lock.yaml file is created on the same directory as the plugins.txt or plugins.yaml, in which plugins were listed to be downloaded and the listed plugins as well their dependencies are written in the lock file.

Submitter checklist

• 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