[New module system] Incorrect IR after module insantiation

[yav]

To reproduce:

1. Checkout cryptol-specs
2. Start cryptol
3. :set coreLint=on
4. :load Primitive/Keyless/Hash/SHA2/SHA512.cry

This needs more investigation, but the cause might due to the fact that when we instantiate a module we substitute concrete types into the schemas of some things. This might cause certain predicates in the qualified types to become True and thus disappear, but then the underlying term is incorrect because it expects evidence for something which is now gone.

[yav]

The comment above describes the problem. Here is a smaller example to reproduce it:

submodule F where
  parameter
    type n : #

  f : (2 < n) => ()
  f = ()

submodule M = submodule F where
  type n = 8

Main> :set debug=on
Main> :r
Loading module Cryptol
Loading module Main
module Main
import Cryptol
  
/* Not recursive */
Main::M::f : ()
Main::M::f = \(True) -> ()

[yav]

There's also an issue if we change the above example to instantiate F with 1 in which case the predicate would become False. Apparently coreLint does not like that, so we need to investigate why that is.