[APPS-544] Create translation yml files from json

:koala: :+1: 

Generate a Zendesk translation file from en.json

- [x] Parse en.json to get full translation keys
- [x] Generate yml based on template
- [x] Sanitise app / package name from user input
- [x] Integration test template generation

`zat translate create`

/cc @zendesk/quokka