Add MAIB Reports to routes.rb
Add schema for MAIB Reports

Facets for MAIB Reports are vessel type, report type and date of
occurrence.
Add model for MAIB Report

This commit also adds the builder, factory and validator.
Add services for MAIB Reports

Also adds services for the MAIB Report Attachments.
Define repository for MAIB Reports
Add observers for MAIB Reports

This also adds the formatters for the artefact and for indexing by
Rummager along with all the necessary calls for these.
Adding views for MAIB Reports
Add permission check for MAIB Editors + nav link
Add spec for MAIB Report model
Testing MAIB Report workflow

Creating, editing, publishing and withdrawing MAIB Reports are tested by
these cucumber tests.
Bump govuk_content_models to 22.1.2

This version bump includes the MAIB Report artefact kind
Merge pull request #291 from alphagov/add-maib-reports

Add maib reports
Remove object-specific builders for parameter-specific builders

Many of the builders that inherit from `SpecialistDocumentBuilder`
tend to do the same thing which can be summarised as the following bit
of code:

```
def call(attrs)
  super(attrs.merge(document_type: "some_document_type_label"))
end
```

They're adding a `document_type` key to the `attrs` hash we pass in.

Rather than create a number of objects for the same task, instead
provide the difference as a parameter so that we can better understand
not only what's different about our builders, but also what's the
same.