feat: Create Release Pipeline

[tiagoapolo]

Thanks for submitting a PR! Please check the boxes below:

• I have added information to docs/ if required so people know about the feature!
• I have filled in the "Changes" section below?
• I have filled in the "How did you test this code" section below?
• I have used a Conventional Commit title for this Pull Request

Changes

This pull request implements pipeline creation flow for release pipelines, including pipeline stages and on_enter action.
Tasks:

• #5267
• #5268
• #5269

https://www.loom.com/share/ef566337763e4a5e86763d6cf9babc57?sid=eb50c14a-27d7-49d5-8838-db6d0704fc41

How did you test this code?

⚠️ Tested using branch with backend and frontend release-pipe-front-back

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Name	Status	Preview	Comments	Updated (UTC)
flagsmith-frontend-preview	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	May 29, 2025 8:28pm
flagsmith-frontend-staging	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	May 29, 2025 8:28pm

1 Skipped Deployment

Name	Status	Preview	Comments	Updated (UTC)
docs	⬜️ Ignored (Inspect)	Visit Preview		May 29, 2025 8:28pm

[github-actions]

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[github-actions]

Docker builds report

Image	Build Status	Security report
ghcr.io/flagsmith/flagsmith-api-test:pr-5455	Finished ✅	Skipped
ghcr.io/flagsmith/flagsmith-e2e:pr-5455	Finished ✅	Skipped
ghcr.io/flagsmith/flagsmith-api:pr-5455	Finished ✅	Results ✅
ghcr.io/flagsmith/flagsmith:pr-5455	Finished ✅	Results ✅
ghcr.io/flagsmith/flagsmith-private-cloud:pr-5455	Finished ✅	Results ✅
ghcr.io/flagsmith/flagsmith-frontend:pr-5455	Finished ✅	Results ✅