Adding optional param to return URL for manual redirection #3531

Engine component of mobile-native#3531 (closed)

Adds a returnUrl GET parameter to the Zendesk Controller, which bypasses PHP redirection; enabling mobile to redirect a user to the logged-in helpdesk.

https://feat-return-zd-url-3531.minds.io/api/v3/helpdesk/zendesk?returnUrl=true