Budgets Admins experience enhancements

As of today, most of our clients (@OSP) use Decidim for participatory budgets and we have been collecting users (admins in this case) feedbacks for the last few months. All of them concern the difficulty when it comes to process them after the proposal phase has ended. Here a few examples : - "When I exported the proposals, I realized that some of them were actually withdrawn proposals. I had to look for them on the platform again to update my export." -"It was very painful to process 300 proposals (only displaying 15 per page) with no filtering or ordering capacities in the proposals back office" -"To analyze the proposals, we export them and assign them to the administration services qualified to assess their feasibility. Once a service gave its feedback, I had go through all the proposals in the back office to find the one or few proposals I wanted to answer to." We propose to address those admins difficulties through a series of enhancements. We already started to work on some of them, others are still works in progress. You can find them here => https://github.com/OpenSourcePolitics/decidim/milestone/10. We plan to test and iterate on them before considering any merge.