Grab ReplyType from the reply parameters in a route function #6469

Prerequisites

• I have written a descriptive issue title
• I have searched existing issues to ensure the feature has not already been requested

🚀 Feature Proposal

Add utility type or a re-export the type of the ReplyType generic.

Motivation

It would be nice to have a conventional way to grab the type of the reply inferred by a type provider or supplied as a generic argument from inside the route function without having to type it as it's own type name.

Example

async function (request, reply) {
  const result: (typeof reply)['ReplyType']; Or // ReplyType<typeof reply>
}