Add caching to branches API [RUN ALL RSPEC] [RUN AS-IF-FOSS]

Merged Robert May requested to merge cached-branches-api into master

What does this MR do?

Adds caching of rendered JSON entities to the branches API. This results in about a 150ms response time improvement on my GDK, should be roughly similar in production.

Related #330128 (closed)

Screenshots (strongly suggested)

Does this MR meet the acceptance criteria?

Conformity

Availability and Testing

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

  • Label as security and @ mention @gitlab-com/gl-security/appsec
  • The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
  • Security reports checked/validated by a reviewer from the AppSec team
Edited by Robert May