WIP: Generate and symlink gitlab_pages_shared_secret
With gitlab#28781 (closed) we introduced new internal API in the Rails app that will be consumed by GitLab Pages (for more context see &1316 (closed)).
Pages will authenticate requests using JWT issued using a secret that will be shared between Pages and the Rails app. This is the same as how GitLab Workhorse authenticate.
This MR takes care for generating and symlinking the secret. I followed gitlab_workhorse_secret
as an example.
Related to gitlab#28781 (closed).
Edited by Krasimir Angelov