Add Gitaly keyset pagination support to repository tree API

Merged Robert May requested to merge repository-tree-api-pagination into master

What does this MR do?

Adds Gitaly keyset pagination to the repository tree API. This works simultaneously alongside the previous pagination implementation until we can deprecate that in %15.0.

This is a significant performance improvement for returning the tree on large repositories as it cuts the Gitaly responses down to just the specified page size.

Related #331901 (closed)

Screenshots or Screencasts (strongly suggested)

How to setup and validate locally (strongly suggested)

Does this MR meet the acceptance criteria?

Conformity

Availability and Testing

Security

Does this MR contain changes to processing or storing of credentials or tokens, authorization and authentication methods or other items described in the security review guidelines? If not, then delete this Security section.

  • 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