feat: add auth flow

[mattinannt]

What does this PR do?

Fixes # (issue)

How should this be tested?

• Test A
• Test B

Checklist

Required

• Filled out the "How to test" section in this PR
• Read How we Code at Formbricks
• Self-reviewed my own code
• Commented on my code in hard-to-understand bits
• Ran pnpm build
• Checked for warnings, there are none
• Removed all console.logs
• Merged the latest changes from main onto my branch with git pull origin main
• My changes don't cause any responsiveness issues
• First PR at Formbricks? Please sign the CLA! Without it we wont be able to merge it 🙏

Appreciated

• If a UI change was made: Added a screen recording or screenshots to this PR
• Updated the Formbricks Docs if changes were necessary

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Name	Status	Preview	Comments	Updated (UTC)
oss-gg	❌ Failed (Inspect)			Jan 19, 2024 5:07pm

[github-actions]

Thank you for following the naming conventions for pull request titles! 🙏

[github-actions]

Thank you so much for making your first Pull Request and taking the time to improve Formbricks! 🚀🙏❤️
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