FR: Analytics support on watchOS

Please add Firebase Analytics support to SDK on watchOS, so that we can record to Firebase Analytics directly from watch apps in the same way we can on iOS apps.

To my knowledge right now, to record analytics data from a watch app to Firebase Analytics requires proxying through the SDK running on the iPhone. Or else don't use Firebase for analytics and instead record to GA using its web API (there is no GA SDK for watchOS). Or use a non-Google analytics provider that actually does offer a watchOS SDK, like Yahoo's Flurry SDK. Less than ideal for those of us who want to use Firebase Analytics from a watch app.