Show issue weight on milestone view

Problem to solve

As a user, I should be able to see in a glance what are the weight of each of the issues present in the milestone view, in order to better organize my work.

Further details

In the issue board you can see the weight of each issue, it should be the same in the milestone view.

Proposal

Add the weight on each issue and also in the header of the 3 columns (covered by #1532).