Create basic resource output based on membership implementation
This issue encompasses creating the REST API endpoint based on the [membership API endpoint](https://gitlab.eclipse.org/eclipsefdn/it/websites/membership.eclipse.org/-/blob/master/portal/src/main/java/org/eclipsefoundation/membership/portal/resources/OrganizationResource.java#L419), bringing over the [JSON source](https://gitlab.eclipse.org/eclipsefdn/it/websites/membership.eclipse.org/-/blob/master/portal/src/main/resources/working_groups.json), and migrating the tests over. We don't need any of the organization filters, just the pure data from the [WorkingGroupsService class](https://gitlab.eclipse.org/eclipsefdn/it/websites/membership.eclipse.org/-/blob/master/portal/src/main/java/org/eclipsefoundation/membership/portal/service/impl/DefaultWorkingGroupsService.java) as the new service won't have or care about the context of organizations that are applied downstream.
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