App Layout: Add (1) - (3) bubbles, break into three headings, and indent content under headings

[asizemore]

Child issue of #1555

Update the layout of vizs that have a computation (alpha div, abundance, and beta div vizs, really anything that has a computed variable), so that when it's a computation viz, the layout has

1. Bubble numbers 1-3 (same bubble numbers as the subset download modal
2. Break content into the three steps with headings that use app-specific text
3. Indent content under headings

(this issue absorbed tiny issue #1557 )

[nkittur-uga]

Bubble numbers, headings and indents look as expected on feature site. QA is complete.