Add Kino.recompile/0

[jonatanklosko]

🐈

[hugobarauna]

Awesome!

Out of curiosity: why is this in Kino?

[jonatanklosko]

@hugobarauna we were considering integrating it into Livebook, but this would only be justified if we did accurate stale tracking (e.g. in notebook we do ModA.foo, and ModA.foo implementation calls ModB.bar, and ModB changed, then the notebook cell is stale, but ModA did not change). However, that would require a number of changes to both livebook and elixir and possibly have too much overhead still. So we decided to not do the tracking, but add it for Kino for discoverability (so that people don't need to know about IEx.Helpers.recompile/0) and this way we can have the explicit warning.