feat(ufw): Add base ufw instance functionality into terraform

[Mihai-Dinu-Scwarz]

Description

Jira Ticket

This PR adds basic functionality for unified firewall a user being able to access a new resource called ufw instance. It represents a firewall rule.

relates to #1234

Checklist

• Issue was linked above
• Code format was applied: make fmt
• Examples were added / adjusted (see examples/ directory)
• Docs are up-to-date: make generate-docs (will be checked by CI)
• Unit tests got implemented or updated
• Acceptance tests got implemented or updated (see e.g. here)
• Unit tests are passing: make test (will be checked by CI)
• No linter issues: make lint (will be checked by CI)

[SerseusWasTaken]

Hi @Mihai-Dinu-Scwarz , thank you for this contribution.
I created an internal issue for reviewing and testing your PR and we will soon get to it.

Best regards
Jonas from the STACKIT Developer Tools team

[github-actions]

This PR was marked as stale after 7 days of inactivity and will be closed after another 7 days of further inactivity. If this PR should be kept open, just add a comment, remove the stale label or push new commits to it.

[Mihai-Dinu-Scwarz]

This pr should still be reviewed and counted as open. It is awaiting reviews