Allow grouping user content into separate projects

[azasypkin]

Summary

Currently, users cannot group content they create, and it's not a big deal when they have just one application, but if they're dealing with multiple different applications (e.g. freelancers and consultants) it might become cumbersome to navigate and manage completely unrelated content.

As a potential solution, we can introduce a "project" concept, then can group any content user creates:

• Project#1
  • CORS policies
  • CSP
  • Webhooks
  • Certificate templates
• Project#2
  • CSP
  • Webhooks