[refactor]: Lambda Control plane - introduce service (proxy) layer for GitHub API calls

[npalm]

Description

Currently API calls to GitHub API are spread through the module lambda Control Plane. This make it hards

• reuse code
• refactor code
• mock with testing

As improvent a new service layer could be introduced (as own module in libs) that proxy GitHub API calls as a services. It will makes mocking in the test much eadier, as well refactoring and re-use.