feat: Add booking and user creation source

[alishaz-polymath]

What does this PR do?

Add booking and user creation source to be able to identify where a booking or a user creation was requested from (API V1, API V2, Webapp)

• Fixes #XXXX (GitHub issue number)
• Fixes CAL-XXXX (Linear issue number - should be visible at the bottom of the GitHub issue description)

Mandatory Tasks (DO NOT REMOVE)

• N/A I have self-reviewed the code (A decent size PR without self-review might be rejected).
• N/A I have updated the developer docs in /docs if this PR makes changes that would require a documentation change. If N/A, write N/A here and check the checkbox.
• I confirm automated tests are in place that prove my fix is effective or that my feature works.

How should this be tested?

• Make bookings via Webapp, V1 and V2 and notice the creationSource in the DB reflect the same.
• Make user via Webapp, V1 and V2 and notice the creationSource in the DB reflect the same.

Follow-up

I noticed that we're not running any tests in apps/api/v1/test/lib/bookings/_post.test.ts and I'll take care of that as a follow up, including test for the changes here. I have manually confirmed that v1 is working for this, so it should be okay as a follow up, gives me more time to fix that entire suite properly.

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2 Skipped Deployments

Name	Status	Preview	Comments	Updated (UTC)
cal	⬜️ Ignored (Inspect)	Visit Preview		Jan 24, 2025 11:22am
calcom-web-canary	⬜️ Ignored (Inspect)	Visit Preview		Jan 24, 2025 11:22am

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• Workflow #45131.1 latest results