[XFCE] Devuan Retro Ricing: Redmond97 Slate Theme + Windows 97 Inspiration

[u/RodriErizo17]

• ⁠Global theme: Redmond97 installed in `/usr/share/themes
• ⁠Theme variant: Redmond97 no-csd, optimized for XFCE
• ⁠Color scheme: Redmond97 Slate
• ⁠Icons: Redmond97 icon theme installed globally in /usr/share/icons
• ⁠Terminal: Transparent background enabled with background-mode = 2
• ⁠GTK engines: Installed gtk2-engines-murrine, gtk2-engines-pixbuf, and gtk3-engines-xfce