Add option to switch reported speed between Mebibytes (MiB) and megabits (Mb)

[n-engelhardt]

Describe your suggested feature

It'd be nice to be able to switch between the two units by tapping the speed or tapping a button.

Additional details

Mebibytes (currently the way speed is displayed) is useful because that's how the size is shown, so that's useful in the context of the file size.

Megabits, however, are much more useful for gauging current speed relative to the network speed, so you can gauge bandwidth utilization.