Facet for visibility settings

[sseymore]

Descriptive summary

For admins, have visibility settings faceted for easy reference.

Expected behavior

After logging in, admins can facet by the visibility settings.

Related work

https://github.com/OregonDigital/OD2/issues/1350

Accessibility Concerns

N/A

[CGillen]

I haven't found a way to add a facet to the general search based on use roles. That is the search outside the admin dashboard. If the admin dashboard is acceptable to add the filter, this should be doable. I don't think we could lock it down to just admins though, just people that hit the admin dashboard.

@straleyb have you seen a way to conditionally add facets based on user/roles/abilities?