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 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`.

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

This helps reduce complexity for non-connections

Use global IDs when exposing GraphQL resources

Closes #62650

See merge request gitlab-org/gitlab-ce!29080

This exposes all fields named `id` as GlobalIDs so they can be used
across our entire GraphQL implementation.

When the objects loaded are `ApplicationRecord`s. We'll use our
existing batchloading to find them. Otherwise, we'll fall back to the
default implementation of `GlobalID`: Calling the `.find` method on
the class.