* implemented logging of project and system web hooks
* implemented UI for user area (project hooks)
* implemented UI for admin area (system hooks)
* implemented retry of logged webhook
* NOT imeplemented log remover

https://gitlab.com/gitlab-org/gitlab-ee/commit/df6aada2ce096ed3173a54a2da918c143611e023

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

See merge request gitlab-ce!10109

Conflicts:
	app/services/projects/destroy_service.rb
	spec/lib/gitlab/import_export/all_models.yml

Not only tracking auto-cancelling in pipelines,
we'll also track this in jobs because pipelines
could be retried and the information would get lost
when this happened. Also erase auto-cancelling
relation for pipelines when they're retried.