Implement user dropdown menu on project/organization headers

The maintainers list uses overlapping icons, and should be truncated as well, though I think this is a temporary hack only right now. @humitos suggested expanding this list on hover, but given the list also needs to be truncated at some length, I probably would rather a dropdown to show a vertical list of maintainers/teams.

This also gives more room to put a user icon and name, maybe even more metadata too, like read/admin access, etc.

Also, same for the organization owners, team members, etc in similar views. It would probably make sense to have this be a reusable component -- either template reusable or KO view reusable.

Start by locating the project and organization header views that render maintainers, owners, and team members. Review how the current overlapping icon list is truncated and whether a reusable template or Knockout view already exists. Done means those lists use a bounded dropdown with a vertical member list and room for the proposed user metadata.