Shield Params should use our stream-download system

[JSKitty]

Currently, Shield Params are the biggest 'UX bottleneck' for users - with users frequently citing confusion due to the long, seemingly "frozen" state of "Loading SHIELD Params..." and a progress bar that doesn't move.

Even if the params themselves are useless unless downloaded in full (thus, there's no functional benefit of streaming them), the benefit would purely be for UX purposes, letting us display the download in MBs as well as display a real-time progress bar.

Ideally, although this could be a separate PR: we should also try saving Shield Params within IndexedDB, some users report issues of the Cache seemingly not working, and I assume it's due to either using a locked down browser (stricter cache policies) or simply their device is clearing cache frequently - the UX benefit of saving the params permanently is much greater than the small downside of more persistant, but reliable storage usage.