Add Offline Support

[Cyberillc]

Add iso offline use to the website after downloading the iso and save the iso file as cache

[spetterman66]

And how would sectors be streamed?

[RodrigoDornelles]

I believe that PWA tools can be used, without needing to modify anything in the backend, just add workers to the frontend.

[ProgrammerIn-wonderland]

HDA streaming itself can't realistically be done offline (without preloading the entire hda into IndexedDB!) but it is possible to use libv86 offline so I guess cdrom stuff could work, as long as you don't have any streaming