Harmonize Initiative front office filters

Is your feature request related to a problem?

Recently front-office filters for proposals where revamped. It now allows mutlti-select thanks to checkboxes. It allows for more discoverability as you can make more precise selections that the radio button offers.

Describe the solution you'd like

I'd like to revamp the filter box in that logic. I'll take this opportunity to add couple changes so that the filtering is improved :

• add subfilters to closed so that people can filter by status "accepted" "rejected"
• add a filter for initiatives that received an answer

Does this issue could impact on users private data? Ex. issues related with user's sign up/sign in process, verifications, invitations, sensitive data like email, IP addresses, etc.