Add a guide that lists circumstances to use a given widget

We see a lot of people on the flutter/flutter/issues asking questions about which list widget to use for different purposes (e.g., different sized items, for best performance, etc). It would be good to have a one-page tutorial with a table with some ranking criteria across the top and the various choices for lists in rows, with color shading for good/bad results.

cc @dnfield for the idea.