Add support for a zip file storage as a backend in gitlab-pages

Description

In order to prepare for the support of object storage as a backend for GitLab Pages, the first step will be to support serving a pages site from a zip file on the existing file storage backend.

Proposal

This work has already started in this MR which can be used as a starting point for this work.

• Add configurable timeout

Links / references

Related Epic: &1316 (closed)