Draft: Screenshot viewer

Hi, I'm trying to implement #313. This is very much a work in progress, when the signal GsScreenshotCarousel::screenshot-clicked that I created is firing and received in GsDetailsPage I am trying to switch the StackPage to one I created but the application crashes when the state changes. I wasn't able to extract any meaningful logs about the crash from anywhere. Would love to get some help/feedback with this.

EDIT: no longer crashing! working on the implementation still