When rendering a label we want to check 'scoped_label' feature
availability on a project/group where label is being used. For
this reason a label presenter is used in UI and information about
context project/group is passed to this presenter.

That's a straightforward feature flag code removal for 11.10

Update comments about N + 1 Gitaly calls

See merge request gitlab-org/gitlab-ce!27178

To make sure all known issues are linked to the correct epic, I've gone
through the code base, and updated the comments where required.

Backports https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/10161
(code out of ee/ folder).

[CE] Add mutually exclusive labels

See merge request gitlab-org/gitlab-ce!26804

Replaces blockquote fences with \n,
keeping the line numbering intact.

- added suggestions to mock data
- fixed props to be not required

Scoped labels in EE require additional changes in CE code.

Adds the groundwork needed in order to persist multi-line suggestions,
while providing the parsing strategy which will be reused for the
**Preview** as well.