feat: include tuple names in json schema

[k-yle]

Since TypeScript v4.0, tuples can have names (or 'labels'). For example:

type T = [start: number, end: number];

This PR includes these names in the JSON schema

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Please:

• Make your pull request atomic, fixing one issue at a time unless there are many relevant issues that cannot be decoupled.
• Provide a test case & update the documentation in the Readme.md