Initiatives filters enhancement BO

Is your feature request related to a problem? Please describe.

Filter for initiatives are not complete, and could be enhanced by some improvements, in FO & BO.

To prevent further improvements on initiatives filters in FO, we should implement checkboxes, as it has been developed for proposals.

When administrating initiatives, the admin can't sort them by signature number.

Describe the solution you'd like

As a user, I want to be able to access to all initiatives on the same index by clicking on the filters I want.

As an admin, I want to be able to sort initiatives by number of signatures.

Describe alternatives you've considered None

Additional context See linked mockup

Funded by AN

Does this issue could impact on users private data? No