In sidebar, show × on hover on label to remove the label

To quickly remove a label in the sidebar, show on hover an × in the label bubble to remove the label.

Something like this:

Related issue (was also considered here):

• https://gitlab.com/gitlab-org/gitlab-ce/issues/30467

^ Maybe this was just the label filters in the awesome bar

changed milestone to %Next 2-3 months in gitlab-foss

mentioned in issue gitlab-foss#34262 (moved)

added UX in GitLab FOSS label

mentioned in issue gitlab-foss#35947

marked this issue as related to gitlab-foss#35947

marked this issue as related to gitlab-foss#34262 (moved)

moved from gitlab-foss#33507 (moved)