Enable fully typed param decorators

[mull]

Is your feature request related to a problem? Please describe.
It is frustrating that param decorators cannot be fully type checked.

interface User {
  id: string
}

export function CurrentUser() {
  return createParamDecorator<MyContext>(({ context }) => {
    return "I can return whatever I want here"
  })
}

class SomeResolver {
  @Mutation(() => MyType)
  createSomething(
    @CurrentUser() user: User // @CurrentUser() is implicitly `any` type
  ) {
    // ...
  }
}

Describe the solution you'd like
It may be that TypeScript itself is preventing this from happening, but I think this would be a great addition:

export function CurrentUser() {
  return createParamDecorator<MyContext, User>(({ context }) => {
    return "I can no longer return this" // This would fail
  })
}

It seems like the ParameterDecorator type from TS itself may prevent this from happening (I'm brand new to TS metadata)?

Describe alternatives you've considered
Can't think of any alternatives, happy to hear them!

Additional context
I can provide a PR with implementation, tests, and examples, but need a nudge in the right direction.

• Typescript 4.6
• type-graphql 1.1.x
• reflect-metadata ^0.1.13