Migrate working groups list JS to use new API

Currently we use https://membership.eclipse.org/api/working_groups to populate working group lists from the JS. We will need to migrate this to use the new api that is available at https://api.eclipse.org/working-groups. The data structure should be identical, so this should be mainly updating a URL to reference the new endpoint.

This should not be merged in until its confirmed that the WG data in the new API has been updated to whats currently in the membership version of the API.