Utilize constructors to support circular generics for instantiable types.

If the transformer experiences circular generics, the scope descriptor parameter
is now used to preserve a nested state to avoid looping descriptors forever. The
scope enables the generic descriptor to determine whether to emit a new instance
of the extension or to reuse the parent's constructor (which would emit an
instance of the same prototype), i.e.:

```
getFactory("@factory")([{
  i: ["@parameterId"],
  w: function () { return new function () { Object.assign(this, ɵRepository.ɵRepository.instance.getFactory("@factory")([{
    i: ["@parameterId"],
    w: function () { return new this.constructor; }
  }])); }; }
}])
```

…d this

…since such keys may be cached and reused in parallel

A bound state is an indicator whether a new function instance is emitted,
binding this in the current scope. The scope's constructor can then be
referenced with `this.constructor` enabling a reference to the parent
constructor.

…measure

…etween two interfaces

… forked extensions

… context

… singly linked list