Follow repository symlinks when viewing blobs

Problem to solve

A blob can have multiple types, one of which is a symlink. I tried to use one in the Gitaly repository docs in gitaly@18e5575b, but when clicking on a link to render a blob which is of the type symlink, the user is presented with a blob of the link target.

Intended users

• Parker (Product Manager)
• Delaney (Development Team Lead)
• Sasha (Software Developer)
• Presley (Product Designer)
• Devon (DevOps Engineer)
• Sidney (Systems Administrator)
• Sam (Security Analyst)
• Dana (Data Analyst)
• Simone (Software Engineer in Test)
• Allison (Application Ops)

Proposal

GitLab should follow the symlink'ed blob to the target blob.

Permissions and Security

Each user that has access to the repository is expected to always have access to all the blobs in there, so this doesn't change that, nor does it require reachability checks.

Links / references

Rendered link: https://gitlab.com/gitlab-org/gitaly/-/blob/18e5575bf485738a0c9f76765f8e67aae13ef4e7/doc/gitaly-ssh.md