await iframes

[mfulton26]

our team occasionally gets a different screenshot using storycap for pages that use an iframe

I see that storycap awaits various things including CSS; is there intentional support for awaiting iframes to load? if not, can such be added

thank you

[yizumi1012xxx]

I encounter same problem, so I use --verbose option and check debug log.
I notice that storycap wait fetching resource that is used in iframe, but not wait iframe load.
I add play function for wait iframe load.
It work on local browser, but does not work on headless browser environment. (e.g. Github Action)