Add option to scan a specific repo

For now, We support two options
1) Scanning a specific organization
2) Scanning the entire GitHub by star counts

We need an option to scan a specific repo in case organizations have a large number of repositories.

Let's take as an example the scan organization flow:

We get all the repos in an organization and then send them to `download_workflows_and_actions`.

By implementing this issue, we can create a new function called: `download_repo_workflows_and_actions` that will get a single repo (or a list of repos) to be scanned.