[APPS-1905] Using the new requirements JS API to fetch requirements

Used to fetch requirements using /api/v2/, now uses new JS API

:no_entry: **_Depends on https://github.com/zendesk/zendesk_app_framework/pull/284_**

/cc @zendesk/quokka

### References
 - Jira link: https://zendesk.atlassian.net/browse/APPS-1905

### Risks
 - None