Implement repo.pinning logic

   * Ubuntu pinning params allow to be used
     multiply times. In same time, old `list`
     format now allowing to be predictable
     iterated inside jinja

Related-Bug: PROD-21604 (PROD:21604)

Change-Id: If1c0f0f834a296b9a19d0af5fc7673c9229a7ac5
4 files changed