Better user experience related to Consultations/Questions

When listing the questions of a Consultation, the button that links to a Question is the same wether the user has voted it or not. When visiting a Question to vote it, the user must go back to the Consultation page to visit another Question. The proposal is to: - Change button appearance when listing questions in the Consultation page - Add previous/next button when viewing the Question page Some screenshots can be seen at: https://github.com/CodiTramuntana/decidim-som-energia-app/pull/7