This adds a `markdown_field` to our types.
Using this helper will render a model's markdown field using the
existing `MarkupHelper` with the context of the GraphQL query
available to the helper.
Having the context available to the helper is needed for redacting
links to resources that the current user is not allowed to see.
Because rendering the HTML can cause queries, the complexity of a
these fields is raised by 5 above the default.
The markdown field helper can be used as follows:
```
markdown_field :note_html, null: false
```
This would generate a field that will render the markdown field `note`
of the model. This could be overridden by adding the `method:`
argument. Passing a symbol for the method name:
```
markdown_field :body_html, null: false, method: :note
```
It will have this description by default:
> The GitLab Flavored Markdown rendering of `note`
This could be overridden by passing a `description:` argument.
The type of a `markdown_field` is always `GraphQL::STRING_TYPE`.
This suggests possibly related issues when the user types a title.
This uses GraphQL to allow the frontend to request the exact
data that is requires. We also get free caching through the Vue Apollo
plugin.
With this we can include the ability to import .graphql files in JS
and Vue files.
Also we now have the Vue test utils library to make testing
Vue components easier.
Closes#22071