Productionize Object-Storage

Following on the https://gitlab.com/gitlab-org/gitlab-ce/issues/29203 we need to continue our work on Object Storage for Artifacts:

For %9.4:

• have feature compatibility with artifacts stored on local system: implement support for browsing artifacts on object storage: https://gitlab.com/gitlab-org/gitlab-ce/issues/29203#note_30198233,

For %9.5:

• do test drive on production for existing object storage migrating limited set of data,

Stretch :

• make runner to talk directly to Object Storage and upload files there,

changed the description

assigned to @ayufan

changed the description

mentioned in merge request gitlab-workhorse!180 (merged)

mentioned in merge request !2356 (merged)

closed via merge request !2356 (merged)

mentioned in commit 200f9ba8