Fix empty container elements for accessibility

[LDubya]

This pull request remediates the issue where some menu bar and team member project list containers are empty, totaling 274 occurrences on 237 pages, in order to conform to WCAG Success Criteria A 1.3.1: Info and Relationships.

The fix is to ensure that

elements aren't rendered onto the page if they don't have any
• elements to show.

  Liquid templating language makes it necessary to use double iteration in _layouts/member.html. Storing the list output using the {% capture %} tag and then only outputting the

  if the list isn't empty would be ideal, but unfortunately the {% capture %} tag ends up capturing some kind of whitespace, even when {%- -%} is used to trim whitespace.