Migrate existing GraphQL API endpoints to DRF

[functionzz]

Given consultation with the localization team at Mozilla, we have decided to deprecate the current GraphQL API endpoint in favor for REST API endpoints. This means that the endpoint at

https://pontoon.mozilla.org/graphql

should be replaced by:

--Lists all Locales-- https://pontoon.mozilla.org/api/v2/locales

--Gets Individual Locale-- https://pontoon.mozilla.org/api/v2/locales/[code]

--Lists all Projects-- https://pontoon.mozilla.org/api/v2/projects

--Gets Individual Project-- https://pontoon.mozilla.org/api/v2/projects[slug]

--Gets Individual Project Locale-- https://pontoon.mozilla.org/api/v2/[code]/[slug] - i.e project locale

--Term Search Functionality-- https://pontoon.mozilla.org/api/v2/termsearch/?search=””&locale=””

--Translation Memory Search Functionality-- https://pontoon.mozilla.org/api/v2/tmsearch/?search=””&locale=””

The implementation will be conducted in the Django Rest Framework. We also need to take pagination into consideration for these endpoints.