Improve draft note header design

Closes #7920 and #7905

See merge request gitlab-org/gitlab-ee!8503

Store hashed storage paths in the database

See merge request gitlab-org/gitlab-ee!8614

Moves the pending badge into the header.
Enables the toggle resolve button to toggle the resolve status
of a draft note.

Closes https://gitlab.com/gitlab-org/gitlab-ee/issues/7905

Docs: add link to the docs site from /help landing page

See merge request gitlab-org/gitlab-ee!8639

And place #track_project_repository in Projects::CreateService
instead.

A shard is now the proper name for a repository storage, so Shardable
is an acceptable name for defining the repository shard.

This is a more sensible name to make clear it tracks it in the
database and not just saves it on disk.

Instead of having the foreign key `repository_id` in the `projects`
table, have a FK in the `project_repositories` table. This will:

- Reduce the size of `projects` table, which is huge already.
- Make the foreign key constraint `on_delete: :cascade` useful,
  because the `project_repositories` row will be deleted when
  `projects` row is deleted.
- Since the `project_repositories` row can only be created **after**
  the `projects` row (because hashed storage needs a `projects.id`),
  it does not require updating the `projects` row after creating the
  `project_repositories`.
- Make it easier in the future to have a N-to-M relation.

When a new project is created, or migrated to hashed storage,
create/update the project repository row.

Move EE only differences for finders

Closes #8599

See merge request gitlab-org/gitlab-ee!8629

EE port of " Add a rebase API endpoint for merge requests"

See merge request gitlab-org/gitlab-ee!8623

[master] EE Resolve "Personal access token with only `read_user` scope can be used to authenticate any web request"

See merge request gitlab/gitlab-ee!726

[master] Operations settings page visible to reporter users

See merge request gitlab/gitlab-ee!724

[master] Fixed XSS in merge request approvers

Closes #353

See merge request gitlab/gitlab-ee!662

[master] Stored XSS in Operation Page

See merge request gitlab/gitlab-ee!722

[master] Authorize user when listing board resources

Closes gitlabhq#2738

See merge request gitlab/gitlab-ee!721

[master] Resolve: Guest can set weight of a new issue

See merge request gitlab/gitlab-ee!720

[master] Fix IDOR at /drafts/publish/

Closes #356

See merge request gitlab/gitlab-ee!710

[master ee] Fixed ability to comment on and edit/delete comments on locked or confidential issues

See merge request gitlab/gitlab-ee!739

[master] Operations settings page visible to reporter users

See merge request gitlab/gitlab-ee!724

CE upstream - 2018-11-28 18:21 UTC

See merge request gitlab-org/gitlab-ee!8628

[master] EE Resolve "Personal access token with only `read_user` scope can be used to authenticate any web request"

See merge request gitlab/gitlab-ee!726

[master] Fixed XSS in merge request approvers

Closes #353

See merge request gitlab/gitlab-ee!662

[master] Stored XSS in Operation Page

See merge request gitlab/gitlab-ee!722

[master] Authorize user when listing board resources

Closes gitlabhq#2738

See merge request gitlab/gitlab-ee!721