Restore keys (from secure online backup) in background rather than foreground

[HarHarLinks]

Your use case

What would you like to do?

I would like to put the progress window of restoring keys from online backup into background and continue using the app while it is (down)loading them. There should still be a progress indicator somewhere, and maybe a notification when restoration is complete.

Why would you like to do it?

Once your account has a certain age, it will have loads of keys that take a long time to restore. In my case it takes "only" 1-2 minutes but I'm still impatient. (see also #15011, perhaps #19778?)

I would like to keep using the app in the meantime.

This would also solve or work around a couple of other issues

• You can dismiss "restoring keys from backup" modal by clicking on the background whilst restoration is in progress #17950
• UX suggestion (minor): auto-close "Backup restored" message #10451

How would you like to achieve it?

Similar to how room joining can now happen in background.

Have you considered any alternatives?

No response

Additional context

No response

[robintown]

Progress could be indicated with the spinner at the top of the room list

[germain-gg]

I am very much on board with this idea! I have hit this a couple of times and this is a process that will understandly take a little while, but does not have to block a user from performing actions in the app

[richvdh]

It's not even obvious we should have this button. We should maybe instead always download key backups in the background (element-hq/element-meta#2446)