Include InteractiveCodeSearch by default

I think this is a better candidate for something like what I pondered here. I think the efforts to trim down the things that come with Julia are important because they are prerequisite to small binaries and other goals. At the very least, it doesn’t make sense to require an interactive code search tool be installed in a server that is just running Julia scripts.

However, I think we should make “distributions” of Julia where we can roll up useful tools for specific workflows. I haven’t had time to start working on this, but I think it would be great if teachers, companies, etc. could say “Here are the sensible defaults for our use case. I’ve done the work to make sure they are get installed in the right way.”