Propose new Mautic features

We need some engagement from the community to determine the project brief, and make sure that what we build is actually going to work for marketers as well as developers.

Here is the original proposal where you can read a bit more about the specifications that we had previously created: gid://app/Decidim::Proposals::Proposal/8.

We actually accepted it quite sometime ago as part of the resource management initiative (#i-resource-management on Slack) but we've never had a chance to get it off the ground. 

It's a really important feature to help Mautic become much more usable for marketers!