Layout nerdpacks: Create an <EmptyState /> component to make reduce confusion around how the empty state should be used

[danielgolden]

Problem: The is supposed to be replaced with the actual content of the nerdpack you're building. It turns out that's not very clear because I'm finding people are actually placing their content inside of it rather than replacing it altogether. That causes issues (like the one above from office hours).

Solution: So I think I'm going to create an component so it's harder to get this wrong, and include comments both in the component and where the component is used specifying it should be replaced.

Nerdpacks where this needs to be addressed:

• [x] Standard
• [x] T-bone
• [x] 3 col
• [x] 4 col
• [x] 2x2
• [x] 3x2
• [x] 4x2