#768 Rename `Locale` to `Language`
#768 Rename `Locale` to `Language`

- Updated DB migration script

elimu-ai/webapp,literacyapp-org/literacyapp-web,literacyapp-org/literacyapp-web,literacyapp-org/literacyapp-web,elimu-ai/webapp,elimu-ai/webapp,elimu-ai/webapp,literacyapp-org/literacyapp-web