Implement ability to update deploy keys

Closes #3191

See merge request !10383

Avoid repeated queries for pipeline builds on merge requests

See merge request !11888

* master: (524 commits)
  Improve user experience around slash commands in instant comments
  Fix LFS timeouts when trying to save large files
  retryable? is now available for CommitStatus
  Resolve "Documentation of `.gitlab-ci.yml` states incorrect example for variables"
  Fix test failures
  Add slugify project path to CI enviroment variables
  Fixed typo: craeted -> created
  32118 Make New environment empty state btn lowercase
  Expose import_status in Projects API
  32832 Remove overflow from comment form for confidential issues and vertically aligns confidential issue icon
  Fix test failures
  Allow manual bypass of auto_sign_in_with_provider
  Fix keys seed
  Allow users to be hard-deleted from the API
  fixup some classnames and media queries
  Enable the Style/PreferredHashMethods cop
  Lint our factories creation in addition to their build
  Don’t schedule workers from inside transactions
  Allow scheduling from after_commit hooks
  Forbid Sidekiq scheduling in transactions
  ...

Conflicts:
	app/serializers/pipeline_entity.rb
	db/schema.rb
	spec/factories/ci/stages.rb
	spec/lib/gitlab/import_export/safe_model_attributes.yml
	spec/services/ci/create_pipeline_service_spec.rb
	spec/spec_helper.rb