Fix coding style

Improve coding style

Decouple UPDATE and DELETE operations of asset links

Rename links_attributes to assets:links

Rename exposed param and updated spec

Fix spec for mysql unique validation failure

- Add Releases::Links model
- Expose it in release API
- Add integration tests

Avoid extra storage bucket perm and query

See merge request gitlab-org/gitlab-ce!23995

Handle 'git push -o ci.skip'

Closes #18667

See merge request gitlab-org/gitlab-ce!15643

[master] Guest users have access to all Job information via the API

See merge request gitlab/gitlabhq!2717

gitlab-org/gitlab-shell!166 added support for collecting push options
from the environment, and passing them along to the
/internal/post_receive API endpoint.

This change handles the new push_options JSON element in the payload,
and passes them on through to the GitPushService and GitTagPushService
services.

Futhermore, it adds support for the first push option, ci.skip.  With
this change, one can use 'git push -o ci.skip' to skip CI pipe
execution. Note that the pipeline is still created, but in the "skipped"
state, just like with the 'ci skip' commit message text.

Implements #18667

Fixed content-disposition in blob and files API endpoint

Closes #55781

See merge request gitlab-org/gitlab-ce!24078