freezed declares variants as redirecting factories on the base
(`const factory DocState.loading() = DocLoading;`) and blocs emit through
them. `emit(const DocState.loading())` was recorded as emitting
`DocState`, which is never a variant, so no freezed emission matched and
every variant the UI renders was reported by rendered-not-emitted as a
dead branch.
Factory redirects are now also kept by constructor name, and an instance
creation of `Type.ctor` (or an unnamed redirecting factory) is credited to
the class it redirects to, for emissions, `state =` assignments and
dispatches alike.
Reproduced on freezed_style.dart before the fix: DocLoading, DocReady
and DocStale all reported as never emitted; after, only DocStale, which
really is never emitted and stays as the positive control. No change on
nuwayze, tick, dex or word_alive.
