Revamp the revision slider icons, giving them a more interactive appearance.
Review Request #13134 — Created July 5, 2023 and submitted
This adds a splash of color and some refinement to the revision slider
icons, helping make them stand out from nearby text and giving them a
blue-ish appearance indicating that they're interactive. The icons are
two pixels wider, giving them just a bit more of a hitbox.
The grey range indicator is now more of a grey-blue, helping it fit in
with the appearance while also not itself looking interactive or
clashing too much with the slider handles.
Tested on high-DPI and standard resolution screens.