More general use of `who` in definitions

[usaoc]

This is to record an initial thought about more general use of who (in the sense of define/who that binds a who syntax parameter to a defined name) in Rhombus. There seems to be many cases where existing Racket functions expect symbolic names, for example, in make-parameter (see racket/racket#4810). Maybe providing and encouraging the use of who will be a good idea? Ideas are welcome.

[usaoc]

I think a check-like macro (as used internally in Racket) can also be a good idea, and relates to who because both are inspired by Racket-internal macros.