refactor(graphql/lib): definitions generator `defaultTypeMapping` type reinforcement

[Neosoulink]

PR Checklist

• [x] 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
• [x] 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?

Issue Number: #3210

What is the new behavior?

Reinforce the DefinitionsGeneratorOptions.defaultTypeMapping interface for better visual over the allowed types.

Better suggestions over the supported types

Does this PR introduce a breaking change?

• [ ] Yes
• [x] No

Other information

will close #3210