Add support for hiding the main toolbar

[irgendeinich]

Details

• Adds support for hiding the main toolbar using the new hideDefaultToolbar prop. This allows for the old behaviour where the thumbnail bar was shown but the main toolbar wasn't.
• Adds new "Hiding Toolbar" sample to Catalog app.
• Adds new "Default Annotation Setting" sample to Native Catalog app to show how to configure annotation defaults.

Acceptance Criteria

• When approved, right before merging, rebase with master and increment the package version in package.json, package-lock.json, samples/Catalog/package.json, and samples/NativeCatalog/package.json (see example commit: 1bf805f).
• Create a new release (and tag) with the new package version (see https://github.com/PSPDFKit/react-native/releases).

[radazzouz]

The changes LGTM 👍 They don't impact iOS.

On iOS, we already had the ability to hide the toolbar with the existing API, so I've added the Catalog example in e6a758a

[steviki]

The new iOS toolbar hiding Catalog example looks good to me!