Persist unbound type variables into Typ.t and show

[cyrus-]

In the above, the cursor inspector should show "T" with a hole around it, rather than just ?.

[disconcision]

@cyrus- There is already infrastructure around this, though it is only exposed on-hover:

It doesn't work for the case you show though, the type just shows as provenance: Internal. Not sure if this is just an oversight or if there's some delicate type provenance logic around casting here... something to be on the lookout for though