Add input option to do not print empty chapters

[miroslavpojer]

Background

Some users do not want to print empty chapters.

Feature

Add an option to allow not printing empty chapters.
Keep the main goal for default: "Provide maximum information."

[github-actions]

Release notes

• Introduced a new warning chapter for closed not merged PRs.
• Introduced a new logic for filtering out Issues and PRs using user-defined or default labels.
• Introduced a new logic to control whether empty chapters are printed or not.