Make organization navigation item conditional

Moved from

• #299

I made an attempt at this and had success, but the additional logic slowed down all views considerably. I used the organizations template filters to try to get a list of user organizations. This might need some more thought, and perhaps we do this in the UX side of things instead of using display time logic -- using the organization selection workflow or something?

This is working for now though, it's just very explicit for most users that only need one organization.

• When there is only one organization, the menu item should be "Organization" and lead to the detail view for the only org
• When there are more than one organization, go to the listing view
• If the user does not have an organization, perhaps also go to the listing view? This might be the best place to show organization creation onboarding?

Review the existing organization navigation templates and the prior attempt referenced from #299, especially the organizations template filters and their view-time cost. Decide where the organization-count check belongs, then verify the menu destination for zero, one, and multiple organizations without slowing other views.