extend battery names to be more fine-grained

[danirabbit]

Problem

We have 16px of width in symbolic icons and 24px and 38px vertically in color icons to work with for battery levels, but we're currently only using 4 levels. We could be providing much more fine-grained battery levels if we wanted

Proposal

If we stretched the 48px battery icons a couple pixels, we'd have numbers divisible by 8 instead. We could be twice as accurate in showing battery levels

Prior Art

The freedesktop spec only includes battery-low (defined as 20%) and battery-caution (defined as 40%)—Which are apparently being used incorrectly right now. The other icon names we're currently using good, full, and empty are just convention from GNOME.

[NikoKrause]

Adwaita included als more fine-grained battery icons recently: https://gitlab.gnome.org/GNOME/adwaita-icon-theme/-/tree/master/Adwaita/scalable/status

[hanaral]

So are we doing this in tens?