Feature request: support end to end testing by adding testID

[boxabirds]

When doing end to end testing (such as with detox), the more reliable way to identify when a toast has popped up is by looking for the id. In React Native this is exposed as testID. Simply accepting testID as an optional attribute of a toast that then propagates down through to the <View> in toast.tsx (line 326) this would do the trick.