Better loading indicators for mobile

[Zk2u]

I'm not sure if this is just an iOS thing but imagining that ente uses flutter I imagine it's both mobile platforms.

When backing up photos, it would be really nice to have some additional details for assets while they're uploading. For example atm, it just shows a green spinner. It would be nice to have this be a circle displaying progress (even just identical to the current one). For more details, it would be cool to click on the progress spinner and see things such as upload speed, etc, for debugging reasons (perhaps with client's networking rather than the server, for example).

What do you think?