Fixed width on project visibility icon in project list

What does this MR do?

Gives fixed width to the project visibility icons in the project list so that they all correctly line up with each other.

What are the relevant issue numbers?

Closes #19583 (closed)

Screenshots (if relevant)

Reassigned to @jschatz1

@jschatz1 LGTM

Milestone changed to %8.11

Thanks @iamphill

Status changed to merged

mentioned in commit 415159c2

Mentioned in commit tnir/gitlab-ce@415159c2

mentioned in issue #19587 (moved)