Use app bundles when building for macos

I think there may be some reason this isn't desirable alluded to here: https://github.com/bevyengine/bevy_github_ci_template/pull/13#issuecomment-1238796679

But I've been experimenting with this [here](https://github.com/rparrett/pixie_wrangler/blob/main/.github/workflows/release.yaml#L175), and it seems to generally work.

From what I can see the advantages are:
- Works better with the itch app. Unlike with a `.dmg` where pressing "launch" just opens up a folder containing the binary.

And the disadvantages:
- Chrome warns you about the file being unusual when downloading

In both cases, actually running the unsigned app (outside of the itch scenario) seems to require the same amount of effort.

Inizia ispezionando il workflow di build macOS in questo repository e confrontalo con l'esempio in .github/workflows/release.yaml in pixie_wrangler. Esamina la discussione di Bevy collegata per conoscere i motivi per evitare gli app bundle. Il lavoro è completato quando le release macOS usano gli app bundle dove appropriato e il workflow continua a produrre un artefatto utilizzabile per itch.

Scritto dal modello di indicizzazione a partire dal testo della issue.