fix: handle missing repo on archive plugin

[PendaGTP]

Description

This PR fixes several issues with the Archive plugin:

• PR preview changes were not working when only archived status was updated
• Archive plugin now properly archives repositories after syncing other settings
• Archive plugin now unarchives repositories before syncing other settings
• Fixed handling of missing repositories which previously caused errors (e.g: when new repositories needed to be created)
• Added missing event handlers for repository.archive and repository.unarchive

Changes:

• Resolved all issues listed above
• Improved code formatting and linting for Archive plugin
• Enhanced logging and error handling for Archive plugin
• Updated related test cases

Tests Done

• Manual testing of all scenarios related to Archive
• Unit tests

[PendaGTP]

This PR also fixes an additional issue: repository synchronization failing when creating a new repository using .github/repos/new-repo.yml. While both app mode and full-sync mode currently fail (the latter due to archive plugin issues addressed in the open PR #751), this PR specifically addresses the app mode failure by implementing the fixes listed above.

[PendaGTP]

Hi @decyjphr any throughts on this? I have rebased with latest changes.