Define authorized scope of projects for users

The intention is to list projects which an user [has access](https://github.com/elabs/pundit#scopes). This allow the code use `policy_scope(Project)` (as used in [neighborly-api/app/controllers/neighborly/api/v1/projects_controller.rb#L20-L25](https://github.com/neighborly/neighborly-api/blob/e09cbcce8a51cc72a4ca06e875e85ed50eb4400a/app/controllers/neighborly/api/v1/projects_controller.rb#L20-L25)) skipping those hidden for this user.