Shift Trending, Heatmap, Venn Diagram, and Forecasting examples into GA/AA subsites

[gilliganondata]

Really, sorta' overhaul the Examples menu to rely more heavily on the AA/GA subsites.

Those examples could be migrated to work for both AA and GA in the respective subsites, and would then be more readily replicable by users.

We'd still maybe want to keep the Shiny example (heatmap + trendlines), and CausalImpact examples in the menu.