Show unpublishing information on drafts

www.agileplannerapp.com/boards/173808/cards/8902

content designers need to know when a draft is a
fresh draft as opposed to a draft that resulted
from an unpublishing.

this is a temporary fix whilst we create a state
called 'unpublished' to represent such editions.
Add intent presenter.

This will be used to send "intent to publish" messages to the content
store when an item is scheduled.
Publishing presenter for coming_soon format.
Bump gds-api-adapters to 17.2.0.
Wrappers for intent and coming_soon publishers.
Add publishing API worker for scheduled editions.

This is separate from the standard PublishingApiWorker because it has
two separate responsibilities: send an "intent to publish" to the
content-store intent endpoint, and additionally send a "coming soon"
format if there is currently nothing at that path.
Trigger PublishingApiScheduleWorker on scheduling.

Adds some integration tests for schedules.
Add coming_soon schema, plus validation tests.
Tidy up worker and tests.
Rename Intent to PublishIntent

This better matches the language elsewhere (e.g. content_store)
Add some basic documentation
Modify description on organisations of type other

* Modification to describe organisations of type ‘other’ without
reference to the word ‘other’.
* Addition of a helper method to include the organisation’s parental
and child relationships in its description.
* Supporting tests to ensure organisations are described correctly.
Use helper method to describe organisations

Use of the additional helper method to describe the organisation, with
its parental and child relationships.
Tweak test to ensure full coverage

We want to ensure that the publish intent is still sent, just that the "coming
soon" holiding page isn't.
Only expose and test external interface

the publish_coming_soon and publish_intent methods are for internal-use only.
Rename method for consistency and clarity
Remove redundant code

If the find fails, an exception will be raised
Support query params and fragment in redirect URL

Content store has now been changed to support anchor fragments and
query parameters[1].

However the Unpublishing presenter currently strips these off when
sending them to content store[2].

This change ensures that the anchor fragment and query parameters are
preserved.

We use URI::Generic.build to compose the pieces of the URI, rather than
trying to do anything too clever with regexps.

[1] https://github.com/alphagov/content-store/pull/93
[2] https://github.com/alphagov/whitehall/blob/master/app/presenters/publishing_api_presenters/unpublishing.rb#L59
Update all service and info styling

So that it doesn't look out of place on the page. We didn't do this the
first time round because there were no examples of orgs with news
priority links but with a service and info link so it got forgotten.
Merge pull request #1915 from alphagov/small-service-info

Update all service and info styling