Support `setPageName` for iOS

[atwalg2]

Currently the package looks like it only supports tracking changing pages on the Android side of things,
this seems like very important functionality to have on both platforms.

Any time a page change happens on the js side of things, we should be able to send the page information to the native side using something like "setPageName" to track how a user moves through the app. This information is only available on the JS/TS side, and needs to be send to the native side.

Extra info:
The vast majority of react-native community uses the library "react-navigation" to handle navigation within their apps, and page names are only visible in JS/TS.

[vincent-sift]

Thanks @atwalg2 we are aware of this issue and we are working on adding a fix.