Create setting to hide insights on search homepage
Created by: Joelkw
Per this slack thread, it would be useful to the CE team if we can hide code insights from the homepage without disabling it entirely because:
- they still want to demo insights
- they slow down the home page
- they distract from the first intro of "Sourcegraph as search"
These three points in concert make me believe the best solution here is to create a quick settings flag that turns off insights from the homepage (default-on still). We haven't done an exploration of viewing insights/where to view them yet, so I don't want to build a complicated system or make hard-to-undo decisions about how they get revealed.