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`.

Make task completion status available via GraphQL

Closes #62910

See merge request gitlab-org/gitlab-ce!29573

Add specs for task completion status (graphql)

Fix style issues

Changed format of constants in spec

Refactor specs to reduce creation of records

Reduce parameters to merge request creation

Use set's for project and user

Move let's out of it_behaves_like block

Fix description parameter

Fix format of lets

Use dig to get task completion status out of graphql response

Modified rspec output

Add changelog entry

Add the missing check on GraphQL API for project statistics

This exposes `Note`s on Issues & MergeRequests using a
`Types::Notes::NoteableType` in GraphQL.

Exposing notes on a new type can be done by implementing the
`NoteableType` interface on the type. The presented object should
be a `Noteable`.

Since we're not actually  loading commits in that loader, but we're
loading blobs with LFS oids in batch and returning only the oids.

Reduce GraphQL complexity for non-connection fields

Closes #62706

See merge request gitlab-org/gitlab-ce!29165

Add web_url to tree entry in GraphQL API

See merge request gitlab-org/gitlab-ce!28646