We were not calling hook_attrs on the labels correctly. Specs were
passing because the issues under test did not have any labels!

Enables frozens string for the following:

* lib/gitlab/conflict/**/*.rb
* lib/gitlab/cross_project_access/**/*.rb
* lib/gitlab/cycle_analytics/**/*.rb
* lib/gitlab/data_builder/**/*.rb
* lib/gitlab/database/**/*.rb
* lib/gitlab/dependency_linker/**/*.rb
* lib/gitlab/diff/**/*.rb
* lib/gitlab/downtime_check/**/*.rb
* lib/gitlab/email/**/*.rb
* lib/gitlab/etag_caching/**/*.rb

Partially addresses gitlab-org/gitlab-ce#47424.

[10.6] Prevent notes on confidential issues from being sent to chat

See merge request gitlab/gitlabhq!2366
# Conflicts:
#	app/helpers/services_helper.rb

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5620#note_13671791

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5620#note_13672004
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5620#note_13810498

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5620#note_13540099

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

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

- Add `avatar_url`, `description`, `git_ssh_url`, `git_http_url`,
  `path_with_namespace` and `default_branch` in `project` in push, issue,
  merge-request and note webhooks data
- Deprecate the `ssh_url` in favor of `git_ssh_url` and `http_url` in
  favor of `git_http_url` in `project` for push, issue, merge-request and
  note webhooks data
- Deprecate the `repository` key in push, issue, merge-request and
  note webhooks data, use `project` instead

Supports four different event types all bundled under the "note" event type:

- comments on a commit
- comments on an issue
- comments on a merge request
- comments on a code snippet