Add project milestone links to dashboard milestones page

Before we deprecate the dynamic milestone list items from the dashboard page (https://gitlab.com/gitlab-org/gitlab-ce/issues/39545), we should add direct project milestone links to the dashboard page.

This issue does that.

That is, on the dashboard milestone page (e.g. https://gitlab.com/dashboard/milestones), we should have a link that goes directly to https://gitlab.com/victorwu/hello-world3/milestones/1, as an example.

The design is the same as how group milestones currently are displayed on the dashboard milestones list. See https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/22552#note_113560124.

Frontend issue: https://gitlab.com/gitlab-org/gitlab-ce/issues/52376