always emit clutz types in heritage clauses

[evmar]

When there is a type-value conflict, e.g.
interface B {}
const B = 3;
then tsickle doesn't emit a Closure type for the interface.

Then when
class A implements B
tsickle omits the @implements for B, because B doesn't exist.

But when B comes from a Clutz definition, we know that the type
B does exist on the Closure side, and we must emit the @implements.

This change keys off a Clutz-emitted file header to control this.

Partial fix of #1072.

[evmar]

Depends on angular/clutz#926

[evmar]

Post-review note: I had to add the underlying goog.module that we're simulating Clutz for here for the test that verifies Closure compilation to pass. It's just a straightforward JS file, so I think it's harmless to submit.