feat(packages/graphql): resolve field output type by name

[NicolasGn]

PR Checklist

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• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

What is the current behavior?

In a code-first schema definition, we need to import the type of any object field.
This behavior can lead NodeJS module circular import issue because GraphQL philosophy allows (and even encourage in complex schemas) cyclic relations.

Here is tiny project illustrating the problem with a very simple 3 types schema, using a classical GraphQL pattern: https://github.com/NicolasGn/nestjs-graphql-circluar-dependency

What is the new behavior?

To break the circular import, we need to be able to reference a schema type by its name and not exclusively by a type reference.

Does this PR introduce a breaking change?

• Yes
• No

Other information

[NicolasGn]

I'm not sure of where I should write the test for this feature.