guest users can't use issue board focus mode

Summary

Guest users can view issue bords but the focus mode button doesn't show up.

Steps to reproduce

Make guest user and open an issue board.

Example Project

https://gitlab.com/gitlab-org/gitlab-ce/boards

What is the current bug behavior?

No focus button for guest users.

What is the expected correct behavior?

Guests should be able to enable board focus view.

Relevant logs and/or screenshots

none

Output of checks

none

Results of GitLab environment info

none

Results of GitLab application Check

none

Possible fixes

none