feat: add user identities & machine identities to stripe billing

[ShubhamPalriwala]

Description 📣

• Adds versioning in Organization schema as billingVersion where
  • v0 is the current developer based pricing where only users are charged
  • v1 is the new pricing where identities (users & machines) are charged
• Combined limit of 5 for both users as well as machine identities
• Updates & Validates identity limit check on creation & deletion of users as well as machine identities

Type ✨

• Bug fix
• New feature
• Breaking change
• Documentation

Tests 🛠️

Run with the license server locally and test the new limits + combined pricing

# Here's some code block to paste some code snippets

---

• I have read the contributing guide, agreed and acknowledged the code of conduct. 📝

[dangtony98]

Closed because the desired implementation should be such that the Infisical application itself is unaware of any pricing scheme / versioning-related information; it should simply pull back the feature set from the license server including any identity-related restricitons.

This logic should be fully centralized on the side of Stripe / license server so that, for example, if we needed to know who is on the so-called billing version v2 then we can obtain that information in Stripe instead of querying the DB here.