iFrame swapper needs to more intelligently wait on Code Components before swapping

Overview

It's been observed that in some circumstances, when there are Code Components on the page, the iFrame swapper is switching to the other iFrame before the code components have (fully) rendered.

I have not seen the behaviour personally, however I suspect it can be reproduced with either slower network or disabling browser cache or a combo of both.

Proposed resolution

@effulgentsia gave some suggestions in 🐛 Overlay and iFrame flicker on updating props values Active , #12, #13 and #14

User interface changes