Instead of using state-foo icons, use the corresponding emblems because
they are larger and don't have the 'cloud state' background.
Keep the existing names because I don't feel like churning
more of the codebase than necessary.
These new icons are from KDE Neon breeze-icon-theme 5.40, e.g.
breeze-icon-theme: /usr/share/icons/breeze/emblems/8/emblem-error.svg
This also adds ImageRegistry, a SVG cache, a bunch of utility functions
for shared pixmaps in CalamaresUtilsGui and renames several qrc files
in viewmodules.
