feat(ios): FirstVoices: Use the metadata in kmp.json to associate with languages and versions

Splitting this PR for iOS from #2036

@[mcdurdin](https://github.com/mcdurdin) writes
mcdurdin commented [on Sep 3, 2019](https://github.com/keymanapp/keyman/issues/2036#issue-488383910)
Is your feature request related to a problem? Please describe.

> FirstVoices Keyboards currently does not make use of the BCP 47 language tags in the kmp data included with keyboards. In the future, we'd like to make this possible, and reduce the amount of data required in the source keyboards.csv file for correct deployment of the app.

At some point the FirstVoices iOS app should
* Use kmp.json for language / version info
* Use keyboards.json for region info

then we can remove keyboards.csv from this repo and the keyboards repo