Use button group for actions in the Group Security Dashboard

Problem to solve

We have three buttons to perform actions in the Group Security Dashboard:

It could be turned into a button group:

Further details

Originally discussed in https://gitlab.com/gitlab-org/gitlab-ee/issues/6709#note_118724823

Proposal

Replace the three buttons with a button group.

Design

All hover states
With no actions taken (default grouping)
If vulnerability was dismissed
If issue was created
If vulnerability was dismissed and issue was created

Popover detail and hover states

Design Specs:

See design specs here

Note:

designs show with new info icon implimented with: https://gitlab.com/gitlab-org/gitlab-ee/issues/8506