This makes it possible to workaround a bug in `safe_constantize` which
caused a `LoadError` exception when doing

```
"Pipeline".safe_constantize
LoadError: Unable to autoload constant Pipeline, expected
/home/grzesiek/gdk/gitlab/app/models/ci/pipeline.rb to define it
```

See https://github.com/rails/rails/issues/28854 for more details.

- Expand PipelinesFinder functions

This reverts commit 0a60cdb110754a5e894ca1a2aa619842f2d98d1a.

This reverts commit e00fb2bdc2090e9cabeb1eb35a2672a882cc96e9.

# Conflicts:
#	.rubocop.yml
#	.rubocop_todo.yml
#	lib/gitlab/ci/config/entry/global.rb
#	lib/gitlab/ci/config/entry/jobs.rb
#	spec/lib/gitlab/ci/config/entry/factory_spec.rb
#	spec/lib/gitlab/ci/config/entry/global_spec.rb
#	spec/lib/gitlab/ci/config/entry/job_spec.rb
#	spec/lib/gitlab/ci/status/build/factory_spec.rb
#	spec/lib/gitlab/incoming_email_spec.rb

This reverts commit cb10b725c8929b8b4460f89c9d96c773af39ba6b.

Fix broken test

```
Endpoint: /group/project/pipelines/id/stage.json?stage=name

Call: stage_namespace_project_pipeline_path(pipeline.project.namespace, pipeline.project, pipeline, stage: stage.name)
```

Adds tests for the Linked Tabs class

Removes event listener

Adds builds

Pass `updated_at` to get only incremental changes since last update

This change simplifies a Pipeline processing by introducing a special new status: created.
This status is used for all builds that are created for a pipeline.
We are then processing next stages and queueing some of the builds (created -> pending) or skipping them (created -> skipped).
This makes it possible to simplify and solve a few ordering problems with how previously builds were scheduled.
This also allows us to visualise a full pipeline (with created builds).

This also removes an after_touch used for updating a pipeline state parameters.
Right now in various places we explicitly call a reload_status! on pipeline to force it to be updated and saved.