Adding the necessary API for the new /snippets Restful resource
added with this commit. Added a new Grape class `Snippets`, as
well as a `PersonalSnippet` entity.

Issue: #20042
Merge-Request: !6373
Signed-off-by: Guyzmo <guyzmo+gitlab+pub@m0g.net>

The coverage wasn't exposed yet, now it is but only for detailed
requests to save queries on the database.

[e44da1c] Add Label API expected keys to tests

[ac929c8] Update Label API documentation

Signed-off-by: Rémy Coutable <remy@rymai.me>

The UI allows to define a token to validate payload on the target URL,
this patch adds the feature to the API.

 Now exposed:
 - push_events
 - tag_push_events
 - enable_ssl_verification
 - token

 Fixes gitlab-org/gitlab-ce#23307

When we updated gitlab_git to 10.4.1, `tag.target` changed from pointing
to the sha of the tag to the sha of the commit the tag points to. The
problem is that only annotated tags have `object_sha`s, lightweight tags
don't (it's nil), so (only) in their case we still need to use
`tag.target`.

  - Includes documentation and tests

This will allow the Koding app to enable the integration itself once is has authorized an admin user using the application secrets.

add pipeline ref, sha, and status to the build API response

add tests of build API (pipeline data)

change API documentation for builds API

log change to builds API in CHANGELOG

CHANGELOG: add reference to pull request and contributor's name

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: Rémy Coutable <remy@rymai.me>

Groups can enable/disable LFS, but this setting can be overridden at the project level. Admin only

- Required on the GitLab Rails side is mostly authentication and API related.

Use NotificationSetting::EMAIL_EVENTS for params

Fixes #20456.