Align annotations changed with ios

[nickwinder]

Fixes : https://github.com/PSPDFKit/react-native/issues/196

Details

This PR changes annotation events on UWP to pass back a list of annotations like Android and iOS does.

Acceptance Criteria

• When approved, right before merging, rebase with master and increment the package version in package.json, package-lock.json, and samples/Catalog/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).

[steipete]

lgtm!