[racket] module-path=?

Funnily enough, I asked Matthew a similar question earlier this
evening.  Without permission, I quote his reply:

>> When do two module designators designate the same module?

> Do you mean "the same for any installation" or "the same for the
> current installation"?
>
> For the former: normalize each module path using `collapse-module-path'
> and compare the results using `equal?'.
>
> For the latter: build a module path index using
> `module-path-index-join', resolve it using `module-path-index-resolve',
> and then compare the resolved paths using `eq?'.