Reify type refs in inherited method bodies

[sylvanc]

Previously, a trait that had a method body that used a typearg as
a class to call a constructor on would fail when the method body
was inherited, as the TK_REFERENCE wasn't reified. Now the
TK_REFERENCE is reified as a TK_TYPEREF.

[jemc]

FYI, this PR was the cause of the CI problems with #1715. I'm still trying to figure out how to resolve them.

[jemc]

Okay, I figured out a way to deal with this change in #1715, but I'm now getting a compiler error with the test case you added that I think is legitimate:

trait T1
 new val create()

trait T2

primitive P is (T1 & T2)

trait T3[A: T1 val]
 fun foo(): A =>
   A

class Baz is T3[(T2 & P)]
 fun bar(): P => foo()

Error:
can't call a constructor on a type intersection: (T2 ref & P val)
   A
   ^

I'm going to replace the (T2 & P) type arg in the test case with just simply P, so that we're not calling a constructor on a type intersection - is that okay?

[sylvanc]

Hmm, interesting. This was allowing a constructor call, as it was finding the constructor on P. But we could pass it some (P1 & P2) as a type argument (an unfulfillable type arg!) and it would pick one of the constructors, which is wrong.

So yes, please do make that change! Thanks :)